[Custom Key Glyph] Show function row keys according to key glyph

1. Get shortcut sources from keyboard key glyph map, only show function row keys if the map contains it
2. Add hardware defined shortcuts to the Shortcut source so they will be displayed in shortcut helper.

Testing result:
No function row key for keyboard that does not have key glyph: https://screenshot.googleplex.com/Ak6oZGzSWJDSRXr
Show hardware defined shortcut if any: https://screenshot.googleplex.com/5TBevsyNDtoLjaX

Bug: 376433516
Test: SystemShortcutsSourceTest
Test: InputShortcutsSourceTest
Flag: com.android.systemui.shortcut_helper_key_glyph
Change-Id: I8991a9ff33fa6bd06fef4781cc3474c75d3d0bdf