Add File Handling `launch_type` field to manifest

Bug: 1304003

Change-Id: I42b6e138b6de26afab977cc97ca050050d2d3d26
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3518293


Reviewed-by: Daniel Murphy <dmurph@chromium.org>
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Commit-Queue: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/main@{#981399}