feat!: support for metaprotocol types (backport #2960)

[mergify]

This is an automatic backport of pull request #2960 done by Mergify.
Cherry-pick of 3ae75ed has failed:

On branch mergify/bp/release/v15.x/pr-2960
Your branch is up to date with 'origin/release/v15.x'.

You are currently cherry-picking commit 3ae75ed.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	new file:   .changelog/unreleased/features/2960-add-metaprotocols-support.md
	new file:   .dockerignore
	modified:   app/modules.go
	new file:   docs/docs/metaprotocols/README.md
	new file:   docs/docs/metaprotocols/_category_.json
	new file:   proto/gaia/metaprotocols/extensions.proto
	modified:   tests/e2e/chain.go
	modified:   tests/e2e/e2e_bank_test.go
	modified:   tests/e2e/e2e_exec_test.go
	modified:   tests/e2e/e2e_test.go
	new file:   x/metaprotocols/README.md
	new file:   x/metaprotocols/module.go
	new file:   x/metaprotocols/types/codec.go
	new file:   x/metaprotocols/types/extensions.pb.go
	new file:   x/metaprotocols/types/keys.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	added by them:   .changelog/v15.0.0/dependencies/2960-add-metaprotocols-support.md

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

---

Mergify commands and options

More conditions and actions can be found in the documentation.

You can also trigger Mergify actions by commenting on this pull request:

• @Mergifyio refresh will re-evaluate the rules
• @Mergifyio rebase will rebase this PR on its base branch
• @Mergifyio update will merge the base branch into this PR
• @Mergifyio backport <destination> will backport this PR on <destination> branch

Additionally, on Mergify dashboard you can:

• look at your merge queues
• generate the Mergify configuration with the config editor.

Finally, you can contact us on https://mergify.com

[mergify]

Cherry-pick of 3ae75ed has failed:

On branch mergify/bp/release/v15.x/pr-2960
Your branch is up to date with 'origin/release/v15.x'.

You are currently cherry-picking commit 3ae75ed.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	new file:   .changelog/unreleased/features/2960-add-metaprotocols-support.md
	new file:   .dockerignore
	modified:   app/modules.go
	new file:   docs/docs/metaprotocols/README.md
	new file:   docs/docs/metaprotocols/_category_.json
	new file:   proto/gaia/metaprotocols/extensions.proto
	modified:   tests/e2e/chain.go
	modified:   tests/e2e/e2e_bank_test.go
	modified:   tests/e2e/e2e_exec_test.go
	modified:   tests/e2e/e2e_test.go
	new file:   x/metaprotocols/README.md
	new file:   x/metaprotocols/module.go
	new file:   x/metaprotocols/types/codec.go
	new file:   x/metaprotocols/types/extensions.pb.go
	new file:   x/metaprotocols/types/keys.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	added by them:   .changelog/v15.0.0/dependencies/2960-add-metaprotocols-support.md

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[MSalopek]

Had to manually move files in the .changelog directory. Parts of the cherry pick failed and changelog was messed up.