Fix duplicate file name generated by GenerateHWIntrinsicTests_General…

….cs (#92954)

When building the runtime tests we get a lot of warnings like this:

> CSC : warning CS2002: Source file '/__w/1/s/artifacts/tests/coreclr/obj/AnyOS.x64.Checked/Managed/JIT/HardwareIntrinsics/General/Vector256_1/Vector256_1_ro/Vector256_1_ro/gen/op_LeftShift.Byte.cs' specified multiple times [/__w/1/s/src/tests/JIT/HardwareIntrinsics/General/Vector256_1/Vector256_1_ro.csproj] [/__w/1/s/src/tests/build.proj]


It turns out that we were generating the same file name for multiple test cases (specifically when using VectorImmBinaryOperatorTest.template), added some validation to the test generator so we throw an error in this case.

A few test cases also needed fixing so they compiled due to a missing closing parenthesis.