Refines OpName emission to only target Global Variables, Functions,
Function Parameters, Local Variables (allocas/phis), and Basic Blocks.
This reduces binary size and clutter by avoiding OpName for every
intermediate instruction (arithmetic, casts, etc.), while preserving
readability for interfaces and program structure.
Also updates the test suite to align with this change:
- Removes OpName checks for intermediate instructions.
- Adds side-effects (e.g., volatile stores) to tests where instructions
were previously kept alive solely by their OpName usage.
- Updates checks to use generic ID matching where specific names are no
longer available.
- Adds debug-info/opname-filtering.ll to verify the new policy.
