[MachineOutliner] Annotation for outlined functions in AArch64

- Adding changes to support comments on outlined functions with outlining for the conditions through which it was outlined (e.g. Thunks, Tail calls)
- Adapts the emitFunctionHeader to print out a comment next to the header if the target specifies it based on information in MachineFunctionInfo
- Adds mir test for function annotiation

Differential Revision: https://reviews.llvm.org/D78062