[ts] Type-check ui/View.js with TypeScript
[ts] Type-check ui/View.js with TypeScript

Similar to other Extension descriptors, this CL introduces a subclass
of RuntimeExtensionDescriptor thats never construted and only used
for type-checking various properties that can be defined in
module.json for views.

R=dba8716ee7f8d16236046f74d2167cb94410f6ed@chromium.org

Bug: chromium:1011811
Change-Id: I4f8e95c9d6875ef99933c683e35a6be4c4776907
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2364357
Commit-Queue: Simon Zünd <38944668e9e2ca98ccd0275b53370f90fa55c113@chromium.org>
Reviewed-by: Tim van der Lippe <dba8716ee7f8d16236046f74d2167cb94410f6ed@chromium.org>

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