Move vesting accunt out of x/auth

[robert-zaremba]

Summary

As we know, x/auth is overloaded. It's primary functionality should be account authentication. But it contains much more.

Problem Definition

Recently we had a problem with x/auth migration where vesting account were vanished: #10591

Proposal

Move vesting account feature from x/auth to x/vesting and enable more feature development in a new module.

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[robert-zaremba]

cc: @AmauryM , @aaronc

[amaury1093]

duplicate #9958 ? We can close that one though, because this one has a description.

[robert-zaremba]

Thanks, I will close this one and move documentation to the #9958