Update Staker requirements and BatchHeader::MAX_CERTIFICATES

[raychu86]

Motivation

This PR updates the minimum validator/delegator stakes and also the BatchHeader::MAX_CERTIFICATES:

MIN_VALIDATOR_STAKE: 1_000_000 credits -> 10_000_000 credits
MIN_DELEGATOR_STAKE: 10 credits -> 10_000 credits
MAX_CERTIFICATES: 200 -> 10

Note that Committee::MAX_COMMITTEE_SIZE and BatchCertificate::MAX_SIGNATURES will also be changed because they are equivalent to BatchHeader::MAX_CERTIFICATES.

[raychu86]

@ljedrz @niklaslong @joske There seems to be an issue with how Committee::MAX_COMMITTEE_SIZE and BatchCertificate::MAX_SIGNATURES are being set in testing. They do not properly use the cfg(test) value of BatchHeader::MAX_CERTIFICATES when running the tests (they use 10 instead of 100).

Would you happen to have a cleaner way to do this rather than adding the cfg flags to both MAX_COMMITTEE_SIZE and MAX_SIGNATURES?

[ljedrz]

@raychu86 I usually prefer to introduce a test feature and then apply a #[cfg(feature = "test")] attribute where applicable; that way, as long as the crate is consistently imported as a dev-dependency with that feature enabled, it doesn't matter how the test is executed - the attribute applies.

edit: since I see that this is also in place, I would check if the crate in question is consistently imported as a dev-depencency with the test feature in the crates where the tests reside.

[d0cd]

LGTM! Left a minor nit.