Generate correct types for Dataset source transformations on backend.

[jmchilton]

This should cleanup vue-tsc errors generated because of the unknown action types in dataset sources.

I think someone used the groomer messages I wrote for various datatypes to use an enum when defining the datatype_ext field on the frontend (the stub in api/index.ts this is replacing) - but I don't think that is appropriate. Galaxy deployers can deploy custom datatypes and custom groomers - so I think a string is a more appropriate type (we have enough references to datatype extensions that some sort of string alias would make sense potentially, but not this enum IMO). The enumeration was groomers we had nice little messages for - not the realm of what is or should be possible.

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.

[jmchilton]

These test failures all seem unrelated.

[mvdbeek]

Thank you @jmchilton!