initiate phasing out of the coin_solutions name in JSON structs

[arvidn]

in favor of coin_spends.

Purpose:

The end goal is to remove the special case JSON logic in SpendBundle.

Current Behavior:

The JSON field is just called coin_solutions.

New Behavior:

There are two fields in the JSON struct, both coin_solutions and coin_spends.

[coveralls-official]

Pull Request Test Coverage Report for Build 7262177764

• 3 of 3 (100.0%) changed or added relevant lines in 2 files are covered.
• 104 unchanged lines in 10 files lost coverage.
• Overall coverage decreased (-0.1%) to 90.444%

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Files with Coverage Reduction	New Missed Lines	%
tests/core/util/test_lockfile.py	1	91.09%
chia/full_node/full_node.py	2	84.32%
chia/rpc/rpc_server.py	2	87.71%
chia/timelord/timelord_api.py	2	87.85%
chia/server/node_discovery.py	4	77.84%
chia/wallet/wallet_node.py	6	87.65%
chia/full_node/full_node_api.py	8	77.16%
chia/server/server.py	8	79.66%
chia/timelord/timelord_state.py	20	69.47%
chia/timelord/timelord.py	51	73.67%

Totals
Change from base Build 7254734138:	-0.1%
Covered Lines:	93748
Relevant Lines:	103607

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💛 - Coveralls

[wjblanke]

aok