Use Pumpkin WASM in Dictation for development.

Ports Pumpkin WASM generated files to Dictation, which
are extracted into the build when the build arg
enable_pumpkin_for_dictation is set to true. The default for this
arg is false, so no changes will be made unless a developer
explicitly includes Pumpkin.

Included Pumpkin commands match the existing Dictation commands
and files were generated from google3 at cl/408446696.

To run this change you must also include when running:
--enable-experimental-accessibility-dictation-extension
--enable-features=ExperimentalAccessibilityDictationCommands

Test: Dictation tests pass with GN args set to true or false.
Bug: 1264544
Change-Id: I373c1ee4e5b979c9c87c9e4fa6ef0873381ad027
AX-Relnotes: N/A
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3256362
Reviewed-by: Akihiro Ota <akihiroota@chromium.org>
Commit-Queue: Katie Dektar <katie@chromium.org>
Cr-Commit-Position: refs/heads/main@{#942013}