[res] Optimize idmap data initialization in OMS

- Only load overlayable definitions for the needed apks
  intead of parsing their all resource tables

- Don't load any overlayable definitions for checking
  actor policies if no actor policies are defined for the
  device. Almost no one defines any

- Reduce the number of allocations for the most common
  operations in overlay settings

Bug: 282215580
Test: system boot + perf trace
Change-Id: I62d19761686d84b7dc643ef1f35588449a61cfbd