Create ABCI++ branch with celestia specific changes

[evan-forbes]

We should create a release branch that incorporates all of the necessary celestia specific changes with all of the changes made so far with upstream's ABCI++ branch

[liamsi]

What is the status/purpose of this? If we want to diff between this and upstream, we can do so from our main branch and look at the abci++ changes manually?

[evan-forbes]

I think was meant to be closed by #631

Closes #623

but the format was wrong so the github hook didn't pick up on it. Any future changes related to ABCI++ should be incorporated via cherry-picking changes from an old celestia release branch onto a branch based on some stable/release branch of tendermint