bruschetta: Implement LaunchAppWithIntent.

This lets Files App "Open With" bruschetta apps.

- Factor out intent filter code into guest_os_apps.
- Move intent filter tests from Crostini to GuestOS code.

Bug: b:265601951
Test: Manually on a DUT: Files App -> "Open With" -> a Bruschetta app.
Change-Id: Iec51868c95067365b425f5a73d552a32e5f89d55
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4302311


Commit-Queue: Emil Mikulic <easy@google.com>
Reviewed-by: David Munro <davidmunro@google.com>
Reviewed-by: Josh Simmons <simmonsjosh@google.com>
Reviewed-by: Fergus Dall <sidereal@google.com>
Cr-Commit-Position: refs/heads/main@{#1118503}