Add (sub) workflow creation from selection

[ElectronicBlueberry]

Implements #20411

Allows creating a new workflow from a selection, or extracting a selection into a sub-workflow, maintaining connections.

In draft as it still needs tests. Will also add screenshots and recordings to this PR at a later point.

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.