Fix binary fetching script

Usage related changes

The binary fetching script could so far only download the artifacts of latest main workflow, which is a problem if its commit message contains [skip ci]. Now it defaults to the latest successful main workflow, and also supports providing a workflow ID via scripts/fetch_ci_binaries.py --workflow <ID>.
Readme also improved.

[x] Checked the relevant parts of development docs
[x] Applied formatting - ./scripts/format.sh
[x] No linter errors - ./scripts/clippy_check.sh
[x] No unused dependencies - ./scripts/check_unused_deps.sh
[x] Performed code self-review
[x] Rebased to the latest commit of the target branch (or merged it into my branch)
[x] Updated the docs if needed, including the TODO section
[x] Linked the issues which this PR resolves
[x] Updated the tests if needed; all passing (execution info)