[RFC] Umbrella v2

[sakulstra]

Context

Currently this repository is used by multiple parties of the aave ecosystem as a boilerplate to create proposals for the agave governance.

Once reviewed, involved parties tend to link parts of this repository(e.g. tests) into their AIP texts which are then stored into immutable ipfs storage.While linking mutable code repositories in an immutable file storage is not a very good idea and should probably solved somehow as well - it's the current reality we live in.
Therefore the master branch is in an "append only" state and cannot be altered in a dramatic way.

With that said, the only way we currently can apply changes to structure etc is by working on a different branch or repository. As this repository still uses master branch, we can switch default to main to be aligned with our other repositories and apply all the structural changes we want.

Tests

Currently tests are added for each proposal although for the most common one being essentially equal.

I don't have a good idea yet on how to solve this.
With a generator we could potentially remove overhead for ppl creating proposals, but thinking there should be a way to have a somewhat generic test and automatically testing only relevant payloads.

Config engine

There is a new version of config engine on address book & aave helpers which would break existing proposals.
If we want to add this on master branch we would need to have the dependency twice.
Therefore when switching to main we have the unique possibility to just "drop" the old config-engine (as in freeze the state on master) and start clean on main.

Misc stuff to do when switching to main

• remove all current proposals & tests to start with a clean state
• rename script to scripts (following forge template)