[XPD] Support Preference style injection

This change implements "style injection" for the following Preferences:

- settingslib_expressive_preference
- settingslib_expressive_two_target
- settingslib_expressive_selector_with_widget

...where "style injection" means that the Preference's layouts do not
directly reference any <style>s, but instead receive them via a
corresponding theme <attr>. For each view within any layout associated
with one of these preferences, there is now both an <attr> and a
corresponding <style> defined for that view.

Additionally, layouts sometimes <include> each other into a parent-child
relationship, and some layouts have more than one possible parent (i.e.,
are <include>d by more than one other layout), and some apps may wish to
vary a child-layout's style depending on its parent. This is supported
here via "theme injection": each layout is passed an "android:theme"
(i.e., a theme overlay) provided from its parent.

For Preferences that have their own project outside of SettingsTheme,
we define Preference's styles within their own project, rather than
within SettingsTheme. But, because SettingsTheme cannot reference those
projects, we have to apply these styles at runtime rather than within
the themes defined in a SettingsTheme resource XML file.

Bug: 375480783
Test: manual
Flag: com.android.settingslib.widget.theme.flags.is_expressive_design_enabled
Relnote: N/A
Change-Id: Ice46cfd45cdc35aa809f78dfebeeafd3bbc22beb