Deprecate FileSystemProvider and RenderNodeProvider

[d-ronnqvist]

Bug/issue #, if applicable:

Summary

This deprecates FileSystemProvider and RenderNodeProvider. They each had their issues.

The clearest sign that FileSystemProvider was a poor API is that both call sites had to reimplement tree traversal to use it:

• FileSystemRenderNodeProvider implemented its own breadth first traversal to iterate over the files.
• StaticHostableTransformer had ~80 LOC of private recursive functions to iterate over the files and determine what their relative paths are.

The issues with RenderNodeProvider are more subtle. Ignoring the issues with the API naming;

• getProblems() was never called, so conforming types created diagnostics that was never presented to the user.
• The issues represented by getProblems() was unexpected errors rather that user-facing diagnostics, so Problem isn't an appropriate type for this information.
• There's only one type that conforms to RenderNodeProvider (not even other conforming types in tests).

What the NavigatorIndex.Builder actually needs would have been better described by some Sequence<RenderNode>.

Dependencies

None.

Testing

Nothing in particular. This isn't a user-facing change.

Checklist

Make sure you check off the following items. If they cannot be completed, provide a reason.

• Added tests
• Ran the ./bin/test script and it succeeded
• [ ] Updated documentation if necessary Not applicable

[patshaughnessy]

Looks like a great improvement 👍

[d-ronnqvist]

@swift-ci please test

[d-ronnqvist]

@swift-ci please test