[25.1] Added file types GocadSGrid and FleflowFem

[tStehling]

Added file types GocadSGrid (.sg) and FleflowFem (.fem) so they can be used in new tools.

How to test the changes?

(Select all options that apply)

• [ x] 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.