Add VIService ST module selection TestApis

Allow VIService to enumerate available underlying ST modules for test
purposes.

Allow VIService to select a specific STModule (via ModuleProperties)
when creating an AOHD.

If no STModule is passed, AOHD will attach to the first available
module -- retaining existing behavior.

Test: Manual verification of assistant recognition flow
Bug: 269358382
Change-Id: Id18240ba8db2c096b5703d068917fc022f0cd61e