[26.0] Check file source template config files for determining conditional dependencies + add constraint for zero-ice

[bernt-matthias]

• Also check file source template config files for determining conditional requirements
• Add a constraint on zero-ice which is a conditional requirement for omero-py xref.

Have tested the 2 commits on my 25.1 release branch (+ cherry picked commits for the omero filesource)

How to test the changes?

(Select all options that apply)

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.

[davelopez]

@bernt-matthias thank you so much!

Looks good to me! And I think this will fix #20483

[bgruening]

Danke @bernt-matthias