Minimal x/gov & x/group Alignment

[aaronc]

There is a longer conversation happening in #9066 around integration and de-duplication of x/gov and x/group, however, in order to bring some immediate benefit from x/authz and x/group to on-chain governance, I propose the following "minimal" changes to x/gov:

• add a root account that x/gov controls
• migrate gov proposal handlers to an array of sdk.Msgs which are only executable by root in their respective modules (i.e. x/param, x/upgrade, etc.)

This will allow x/gov to use x/authz to delegate permissions from root to other "working groups" managed by x/group.

/cc @cmwaters @hxrts @blushi

[aaronc]

Tagging as "Needs Architecture Review" to remind me to present this at this Friday's architecture call.

[aaronc]

@cmwaters green light to move forward on this. We will need to write an ADR to document the changes. Let's chat to coordinate the on that.