[LinkerWrapper] Add an overriding option for debugging (#91984)

Summary:
One of the downsides of the linker wrapper is that it made debugging
more difficult. It is very powerful in that it can resolve a lot of
input matching and library handling that could not be done before.
However, the old method allowed users to simply copy-paste the script
files to modify the output and test it.

This patch attempts to make it easier to debug changes by letting the
user override all the linker inputs. That is, we provide a user-created
binary that is treated like the final output of the device link step.
The intended use-case is for using `-save-temps` to get some IR, then
modifying the IR and sticking it back in to see if it exhibits the old
failures.