CI: for fast CI dev flow - build only changed workflows

[Anton-Latukha]

Description:

Contributions to the CI now have to pass a {test, bench, nix} workflows, which takes ~2 hours per loop & keeps those runners occupied & devs waiting vacuously.

Describe the solution you'd like

(probably by configuring skip-duplicate-actions): Changes to according CI workflow should trigger mostly only that workflow & maybe related ones.

Additional context

I tried to enumerate files directly in d7c1a5a, which in #2506 (comment) is described & has a link to the build.

Later I changed caching only by changing docs & CI still ran into #2506 (comment).

[sloorush]

Hey!
The best solution looks like using skip-duplicate-actions.

But I saw that in #2506 (comment), you have mentioned that it was not working.

I want to work on this. Can you guide me on where to look to solve this?