Consolidate ilasm/main.cpp and ildasm/windasm.cpp

[am11]

There was a discussion about rewriting ilasm/ildasm in C#. If that is not happening in a near future, it would be nice to combine ilasm/main.cpp and ildasm/windasm.cpp main() functions and the arguments parsing code (1.5K LOC), to make the PAL-like code refactoring easier.

Originally posted by @am11 in #76771 (comment)

cc @AaronRobinsonMSFT, @jkoritzinsky

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Issue Details

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There was a discussion about rewriting ilasm/ildasm in C#. If that is not happening in a near future, it would be nice to combine ilasm/main.cpp and ildasm/windasm.cpp main() functions and the arguments parsing code (1.5K LOC), to make the PAL-like code refactoring easier.

Originally posted by @am11 in #76771 (comment)

cc @AaronRobinsonMSFT, @jkoritzinsky

Author:	am11
Assignees:	-
Labels:	area-ILTools-coreclr, untriaged
Milestone:	-