Add invariant tests workflow

[nikitastupin-matterlabs]

What ❔

Introducing the invariant tests workflow.

Why ❔

We want to run invariant tests on schedule. This is possible only if the workflow is on the default branch which is currently main. On the other hand, it doesn't make sense to merge #1237. to main yet because the main doesn't have the target code to test (i.e. the main is far behind dev).

So in order for #1237 to work we need to merge this PR. Later dev will be merged to main adding the missing code.

Checklist

• PR title corresponds to the body of PR (we generate changelog entries from PRs).
• Tests for the changes have been added / updated.
• Documentation comments have been added / updated.

[nikitastupin-matterlabs]

The CI failure doesn't seem to be related to the PR. Never mind, it indeed was a formatting issue. The remaining failure is about coverage so it's not related to the PR.