Improve CI for contracts

[nicolaslara]

Background

CI for contracts within the same workspace runs rust-optimizer once for each contract in the workspace.

Suggested Design

Reorganize the github workflow to ensure the optimizer runs only once per workspace and but that the artifact for all the contracts is uploaded.

This would both improve the speed of the CI runs and simplify the inclusion of the x86 bytecode on PRs

Acceptance Criteria

• All tests pass
• All artifacts are uploaded even if some comparisons fail

[nicolaslara]

It would also be nice to be able to issue a release of the contracts when they are tagged. Similar to: https://github.com/many-things/ibcx-contracts/blob/main/.github/workflows/publish.yaml