[canvaskit] Add initial implementation of generating TS

This adds some initial features for generating the ambient
namespace files (the TS equivalent of .h files) for the
C++ binding files. There are a few tests and it works on
the sample code in tskit.

I split the bindings/ folder into bindings/ and interface/
(for C++ and TS code, respectively).

This can be tested locally by running
make generate && make debug && make serve
and verifying that everything compiles and runs in the browser.

One thing I changed for easier parsing was making a @type
annotation required, with an @optional tag for making a field
or constant optional.

Change-Id: If9c5a664e84fac4c734277cddd7774989a1f7bf8
Bug: skia:11826
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/407476
Reviewed-by: Nathaniel Nifong <nifong@google.com>
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
15 files changed