SuperIlc changes for composite build mode support (#32028)

SuperIlc changes for composite build mode support (#32028)

This change mostly modifies CompilerRunner to support processes
with multiple input paths so that we can run a single Crossgen2
compilation over a larger set of input files. Based on the latest
iteration of my overall composite R2R support change I have now
made it such that SuperIlc passes the framework assemblies to
Crossgen2 using the "-u" option which means "use as input but
don't automatically root all methods in the module i.o.w. compile
only what is transitively reachable from the test app input modules".

Thanks

Tomas