Reduce visibility of state transition types

[arminsabouri]

These inner types were pub(crate)'ed so tests can access the next state by passing persisting. However, using the noop persister can achieve the same thing while reducing boilerplate.

cc'ing @benalleng bc I think you originally contributed the tests I modified

[coveralls]

Pull Request Test Coverage Report for Build 16951875748

Details

• 40 of 40 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.06%) to 85.973%

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Totals
Change from base Build 16943032439:	0.06%
Covered Lines:	7551
Relevant Lines:	8783

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💛 - Coveralls

[benalleng]

uTack. Ahh nice improvement! I must have simply just not understood this was an ideal place for the session persister.

[DanGould]

ACK 6316cbb