[HW][OM] Propose to add functions to query the top OM class

In T1 project, we have multiple configurations, e.g. with or without subsystem, each having different OM hierarchy (the top OM class will be `T1Subsystem_Class` or `T1_Class` respectively).

@sequencer suggests we adding 2 C-API functions for querying:

1. all HW public modules; (so we can append "_Class" and then use the next function)
2. checking if a given OM class name exists.

@mikeurbach What do you think about this idea?

Start by reviewing the T1 configurations and the existing C API surface for OM hierarchy queries. Clarify how public HW modules and OM class names should be represented, then define completion as APIs that enumerate the modules and report whether a supplied OM class name exists.

Written by the indexing model from the issue text.