Support Gradle's `kotlinOptions.freeCompilerArgs`

[bcorso]

Someone ran into this issue in Dagger when trying to set the module name via kotlinOptions.freeCompilerArgs: google/dagger#4493.

In this case, using kotlin.compilerOptions.moduleName works (KSP supports this); however, it would be nice if KSP also checked the freeCompilerArgs as well. At the very least, consider checking the value and throwing an exception with an error message telling users to use the kotlin.compilerOptions API instead.

[hfmehmed]

I am not sure parsing freeCompilerArgs is a good idea. I think the idea of compiler args is to directly pass those to the compiler without parsing or validating them. If the module name is overriden from one of the arguments there then maybe there should be a way to update the corresponding KotlinCompilation.compilerOptions.moduleName object based on that.

@ting-yuan what do you think?