[User Education] Organize components/user_education/common

The folder was getting very big and was getting bigger with the addition
of code for User Education 2.5. In preparation for adding that code,
this CL renames several files and classes to better represent their
function and sorts them all into subfolders.

The renames are all from [X]FeaturePromo[X] to [X]UserEducation[X]
for classes that are now used across User Education instead of just
by the IPH system.

Includes have been changed across the codebase to reflect these moves.

BYPASS_LARGE_CHANGE_WARNING
There is no change in functionality.

Bug: 369887157
Change-Id: I83f8ed9c996c40de3a832bac079ae62667bcc99f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5949424
Reviewed-by: Dominic Battré <battre@chromium.org>
Reviewed-by: Mike Wasserman <msw@chromium.org>
Reviewed-by: Marlon Facey <mfacey@chromium.org>
Reviewed-by: Glenn Hartmann <hartmanng@chromium.org>
Reviewed-by: Mustafa Emre Acer <meacer@chromium.org>
Reviewed-by: Charles Meng <charlesmeng@chromium.org>
Reviewed-by: David Black <dmblack@google.com>
Reviewed-by: Martin Šrámek <msramek@chromium.org>
Commit-Queue: Dana Fried <dfried@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1372807}