[IRSim][IROutliner] Adding support for recognizing and outlining indirect...

[IRSim][IROutliner] Adding support for recognizing and outlining indirect function calls, and function calls with different names, but the same type

The outliner currently requires that function calls not be indirect calls, and have that the function name, and function type must match, as well as other attributes such as calling conventions. This patch treats called functions as values, and just another operand, and named function calls as constants. This allows functions to be treated like any other constant, or input and output into the outlined functions.

There are also debugging flags added to enforce the old behaviors where indirect calls not be allowed, and to enforce the old rule that function calls names must also match.

Reviewers: paquette, jroelofs

Differential Revision: https://reviews.llvm.org/D109448