Misc fixes of get_next_epoch_crosslink_committees

[hwwhww]

1. Fix type hintings
2. Set registry_change clear
3. Formatting

Question: should get_next_epoch_crosslink_committees return slot as well? My intuition tells me that would be helpful.

[djrtwo]

Agreed. Slot will certainly be useful.

Want to add it?
Other than that PR looks good

[hwwhww]

@djrtwo Yes, will do 👍
And also return if the attester is the selected proposer or not.

[djrtwo]

I'm working on these minor updates @hwwhww

[djrtwo]

Changes pushed! Can you do a quick review? then I'll approve and merge

[hwwhww]

@djrtwo
Sorry for the late reply and thanks for the commit! 💯
I was trying to implement it in py-evm (but found that I need to implement other PR first...).
Fixed a tuple layer error and it's runnable in py-evm now.

For the case num_validators=40, epoch_length=16, target_committee_size=1, shard_count=2

validator_index=0
   committee=(31, 39, 0), shard=1, slot=29, is_proposer=True
   committee=(20, 0, 18), shard=1, slot=31, is_proposer=True
#######
validator_index=1
   committee=(17, 1, 35), shard=1, slot=27, is_proposer=False
   committee=(39, 8, 1), shard=1, slot=29, is_proposer=True
#######
validator_index=2
   committee=(9, 19, 2), shard=1, slot=19, is_proposer=False
   committee=(2, 26), shard=0, slot=26, is_proposer=True
#######
validator_index=3
   committee=(5, 3, 11), shard=1, slot=23, is_proposer=False
   committee=(38, 3, 29), shard=1, slot=19, is_proposer=True
#######
validator_index=4
   committee=(15, 12, 4), shard=1, slot=25, is_proposer=False
   committee=(28, 4), shard=0, slot=16, is_proposer=False
#######
validator_index=5
   committee=(5, 3, 11), shard=1, slot=23, is_proposer=False
   committee=(5, 36, 15), shard=1, slot=25, is_proposer=False
#######
validator_index=6
   committee=(6, 32, 23), shard=1, slot=21, is_proposer=True
   committee=(32, 6), shard=0, slot=20, is_proposer=False
#######
validator_index=7
   committee=(36, 7, 10), shard=1, slot=17, is_proposer=False
   committee=(19, 7), shard=0, slot=24, is_proposer=False
#######
validator_index=8
   committee=(18, 8, 33), shard=1, slot=31, is_proposer=True
   committee=(39, 8, 1), shard=1, slot=29, is_proposer=False
#######
validator_index=9
   committee=(9, 19, 2), shard=1, slot=19, is_proposer=False
   committee=(9, 16), shard=0, slot=28, is_proposer=True
#######
validator_index=10
   committee=(36, 7, 10), shard=1, slot=17, is_proposer=True
   committee=(30, 13, 10), shard=1, slot=27, is_proposer=False
#######
validator_index=11
   committee=(5, 3, 11), shard=1, slot=23, is_proposer=True
   committee=(11, 37), shard=0, slot=18, is_proposer=True
#######
validator_index=12
   committee=(15, 12, 4), shard=1, slot=25, is_proposer=True
   committee=(12, 22, 23), shard=1, slot=23, is_proposer=False
#######
validator_index=13
   committee=(13, 34), shard=0, slot=26, is_proposer=True
   committee=(30, 13, 10), shard=1, slot=27, is_proposer=False
#######
validator_index=14
   committee=(26, 14), shard=0, slot=18, is_proposer=False
   committee=(14, 27), shard=0, slot=30, is_proposer=True
#######
validator_index=15
   committee=(15, 12, 4), shard=1, slot=25, is_proposer=False
   committee=(5, 36, 15), shard=1, slot=25, is_proposer=False
#######
validator_index=16
   committee=(16, 28), shard=0, slot=30, is_proposer=True
   committee=(9, 16), shard=0, slot=28, is_proposer=False
#######
validator_index=17
   committee=(17, 1, 35), shard=1, slot=27, is_proposer=True
   committee=(31, 17, 35), shard=1, slot=17, is_proposer=False
#######
validator_index=18
   committee=(18, 8, 33), shard=1, slot=31, is_proposer=False
   committee=(20, 0, 18), shard=1, slot=31, is_proposer=False
#######
validator_index=19
   committee=(9, 19, 2), shard=1, slot=19, is_proposer=True
   committee=(19, 7), shard=0, slot=24, is_proposer=True
#######
validator_index=20
   committee=(24, 20), shard=0, slot=20, is_proposer=False
   committee=(20, 0, 18), shard=1, slot=31, is_proposer=False
#######
validator_index=21
   committee=(21, 27), shard=0, slot=16, is_proposer=True
   committee=(21, 34), shard=0, slot=22, is_proposer=True
#######
validator_index=22
   committee=(37, 22), shard=0, slot=28, is_proposer=False
   committee=(12, 22, 23), shard=1, slot=23, is_proposer=False
#######
validator_index=23
   committee=(6, 32, 23), shard=1, slot=21, is_proposer=False
   committee=(12, 22, 23), shard=1, slot=23, is_proposer=True
#######
validator_index=24
   committee=(24, 20), shard=0, slot=20, is_proposer=True
   committee=(25, 33, 24), shard=1, slot=21, is_proposer=False
#######
validator_index=25
   committee=(30, 25), shard=0, slot=22, is_proposer=False
   committee=(25, 33, 24), shard=1, slot=21, is_proposer=True
#######
validator_index=26
   committee=(26, 14), shard=0, slot=18, is_proposer=True
   committee=(2, 26), shard=0, slot=26, is_proposer=False
#######
validator_index=27
   committee=(21, 27), shard=0, slot=16, is_proposer=False
   committee=(14, 27), shard=0, slot=30, is_proposer=False
#######
validator_index=28
   committee=(16, 28), shard=0, slot=30, is_proposer=False
   committee=(28, 4), shard=0, slot=16, is_proposer=True
#######
validator_index=29
   committee=(38, 29), shard=0, slot=24, is_proposer=False
   committee=(38, 3, 29), shard=1, slot=19, is_proposer=False
#######
validator_index=30
   committee=(30, 25), shard=0, slot=22, is_proposer=True
   committee=(30, 13, 10), shard=1, slot=27, is_proposer=True
#######
validator_index=31
   committee=(31, 39, 0), shard=1, slot=29, is_proposer=False
   committee=(31, 17, 35), shard=1, slot=17, is_proposer=False
#######
validator_index=32
   committee=(6, 32, 23), shard=1, slot=21, is_proposer=False
   committee=(32, 6), shard=0, slot=20, is_proposer=True
#######
validator_index=33
   committee=(18, 8, 33), shard=1, slot=31, is_proposer=False
   committee=(25, 33, 24), shard=1, slot=21, is_proposer=False
#######
validator_index=34
   committee=(13, 34), shard=0, slot=26, is_proposer=False
   committee=(21, 34), shard=0, slot=22, is_proposer=False
#######
validator_index=35
   committee=(17, 1, 35), shard=1, slot=27, is_proposer=False
   committee=(31, 17, 35), shard=1, slot=17, is_proposer=True
#######
validator_index=36
   committee=(36, 7, 10), shard=1, slot=17, is_proposer=False
   committee=(5, 36, 15), shard=1, slot=25, is_proposer=True
#######
validator_index=37
   committee=(37, 22), shard=0, slot=28, is_proposer=True
   committee=(11, 37), shard=0, slot=18, is_proposer=False
#######
validator_index=38
   committee=(38, 29), shard=0, slot=24, is_proposer=True
   committee=(38, 3, 29), shard=1, slot=19, is_proposer=False
#######
validator_index=39
   committee=(31, 39, 0), shard=1, slot=29, is_proposer=False
   committee=(39, 8, 1), shard=1, slot=29, is_proposer=False