CCA: Write video to a temporary file

There is a known issue that when user leaves the app while recording,
there will be an empty file left in the camera folder so that CCA will
throw JS error.

Ideally, it can be solved by implementing mechanism to automatically
delete the empty file when leaving the page without closing the file
stream in File System Access API. However, this feature won't be
supported shortly.

Therefore, this CL provides a workaround to write the file into a
temporary file, just like how we did for video intent, and moves the
file to the target path once the recording is done.

Bug: b:184583382
Test: Manually
Change-Id: Ia6776926c31a1c1218204b5d1d17e311f0cf7e92
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3448628
Commit-Queue: Wei Lee <wtlee@chromium.org>
Reviewed-by: Pi-Hsun Shih <pihsun@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1114982}