This commit refactors the way the compiler transforms .d.ts files during
ngtsc builds. Previously the `IvyCompilation` kept track of a
`DtsFileTransformer` for each input file. Now, any number of
`DtsTransform` operations that need to be applied to a .d.ts file are
collected in the `DtsTransformRegistry`. These are then ran using a
single `DtsTransformer` so that multiple transforms can be applied
efficiently.
PR Close#34235