Pre-release workflows: split CSS and IDL tests or re-run on changes to all patches

[tidoust]

Pre-release workflows run on pushes when the commit may change the contents of the package to release. Currently, that means the CSS worfklow runs when there are changes made to ed/css and ed/csspatches.

The problem is that the CSS (resp. IDL) workflow may also fail when tests fail and tests may fail due to an IDL (resp. CSS) error. When that happens, fixing the offending IDL (resp. CSS) content won't re-trigger the other pre-release workflow automatically.

Two possibilities:

• make both workflows run whenever changes are made to ed/csspatches and ed/idlpatches
• split CSS and IDL tests so that the pre-release workflows only run tests that touch on the contents they're interested in