Refactor the Chrome Apps deprecation code.

The files of the Chrome Apps deprecation work are starting to pile up.
This CL moves all the involved files in a subfolder of the app_service.
This will also simplify the work to remove all the Chrome Apps code
after M168.

Bug: 382199978
Test: autotest c/b/a/app_service/publishers/chrome_app_deprecation_unittest.cc
Test: autotest c/b/a/app_service/publishers/chrome_app_deprecation_browsertest.cc
Test: autotest c/b/a/app_service/publishers/chrome_app_deprecation_kiosk_browsertest.cc
Change-Id: I514a8766f6898c70779938048b0f8945e01be19a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6615042
Reviewed-by: Joshua Pawlicki <waffles@chromium.org>
Reviewed-by: Irina Fedorova <irfedorova@google.com>
Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Commit-Queue: Giovanni Pezzino <giovax@google.com>
Cr-Commit-Position: refs/heads/main@{#1468814}