Root-Canal: Add PDL definition of LL feature bits

The LE local supported features mask was previously defined
as an hexadecimal value, making it complex to read and edit.

Define an enum with LL feature bit values, and initialize the
le_supported_features_ field in DeviceProperties using
an explicit feature list.

Bug: 228326164
Test: VCS PTS tests against Eiffel
Change-Id: I2bbc1b6ac4f6f825437ad889ba910192e6a2d7d8