[24.1] Determine expression tool output extension when input terminal

[mvdbeek]

Fixes #19245 by waiting for the dataset to become terminal if it's a expression.json dataset that we infer the output datatype from.
A slightly better implementation could look at the tool outputs when we generate the command line, which is when we're going to submit and have the terminal datasets ... ?

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.

[mvdbeek]

We might be adding objects to the sqlalchemy session (and maybe even committing them?) before hitting the ToolInputsNotReadyException. This would be a good place to use session.begin_nested() and session.rollback() to undo
staged changes, but I couldn't get that to work without changing the entire commit strategy.