Fix Framework code for HDR bugs

- Refreshes Conversion Mode when Conversion Mode is set to System Conversion and areUserDisabled types are modified. This allows the system to have accurate array of HDR types it is allowed to use.
- Display returns null for HDR capabilities when system is set to Force SDR conversion.
- Simplifies app-requested disabling of HDR conversion (per mOverrideHdrConversionMode).

Bug: 330927371
Flag: EXEMPT bugfix
Test: manual test
Change-Id: I7dc68dde04df6e88ecb08f7afa311bc6340515f6