[move] vouch reputation

[0xzoz]

NOTE: This is a sketch for all practical purposes. No tests have been written for new features (it's a sketch, incomplete, and by definition broken until tested). The previous tests are all passing.

Background
Over the last week(21/04/24) it was observed that the validator set had been increasing quite rapidly since the V7 Hard Fork (more info regarding the hard fork: here). Discussion then started in the #validator-operations channel with some feedback. This PR is intended to hold a template and act as a place for discussion regarding a solution to the hard problem of Sybil Prevention within the validator set of the 0L Network.

Implementation
This makes the execution of features dependent on separate admin actions, but the code deployed in advance for state to begin populating.

I.e if all features are implemented it would require multiple steps for data to get populated, so I implemented with feature flags.

Phase 1:

• Cap number of outbound/given vouches at 10
• Create threshold for min number of required vouches based on validator set size (x/10 + 1)
• Cost to vouch is also dynamic: it's the same as one nominal epoch reward (currently it's basically zero at 0.001 Libra)
• Vouches expire faster (45 days)
• Leaderboard and simple Reputation score begin getting populated (but not implemented)

[soaresa]

Created issue #298 for the first improvements.

[0o-de-lally]

replace with #303