Add build configs for wearable tunables

Low memory devices place special emphasis on memory constraints and cpu
utilization. We want to expose a set of build configurations that allow
these devices to fine tune resource usage during OTA installation.

Our strategy will be the following.
1. For any tunable needed in first stage init, read the .ro prop during
   ota installation, propogate the configuration to SnapshotUpdateStatus
   proto, then read the property from /metadata upon first reboot (since
   .ro properties are not available here)
   2. For tunables which aren't needed until second stage init, read the
   .ro prop directly.

This first CL will just add the build configurations to the build
system. Subsequent CL's will forward the configs to protobufs and
snapuserd daemon

Bug: 332255580
Test: th
Change-Id: I31b36b42f8fba997c772fe1a4ba99b17128b3eca