Generalized Stake Lockup Mechanism

[rigelrozanski]

Stems from #2935 (comment)
also some internal conversations previously.

Rather than have a whole bunch of different modules implement their own ways to lock up funds
It would be awesome to create a generalized staking module, which other modules (including Tendermint staking/slashing as currently implemented) could interface with.

This type of staking could be used as a basis for a variety of new forms of transactions.
possible use cases:

• special transaction authentication. (such an important transaction which exceeds a gas limit)
• tendermint validating (aka current staking)
• governance proposal deposit
• special account permissions such as becoming a "governor" (aka somebody something can delegate voting power for governance proposal voting to)

[rigelrozanski]

@sunnya97

[rigelrozanski]

After further review - I think that the new supply keeper (👏 @fedekunze ) performs most of these functions, actually all besides indexing locked funds per account - however that will soon also be taken care of after the inclusion of module subaccounts (#4732)