This change updates the brand-new in-progress RepositoryForm and

RepositoryFormView classes in JavaScript to use TypeScript and

Spina-based classes instead of Backbone.
This gives us proper type checking for both the model and form, using

interfaces to define available attributes (which also ensures proper

.get() usage on models). It also enables usage of private methods.
Other than porting and documentation, this doesn't fundamentally alter

much of the code. Logic remains the same.
The new code is also now part of the rb/js/admin Rollup bundle, rather

than being listed explicitly in the Pipeline bundle.

Ran through all the various modes in the repository admin form. Didn't

spot any noticeable issues. Verified I was running the new generated

code.