Check QNNPACK support for the platform before running test (#119139)
Do not run test ConstantPropagation.CustomClassesCanBePropagated on a platform where QNNPACK is not supported.
For example, this test fails on M1 Mac because QNNPACK is not supported on M1 Mac:
[----------] 1 test from ConstantPropagation
[ RUN ] ConstantPropagation.CustomClassesCanBePropagated
unknown file: Failure
as described in more details in the issue #88613.
After the PR, test passes successfully as below:
[----------] 1 test from ConstantPropagation
[ RUN ] ConstantPropagation.CustomClassesCanBePropagated
[ OK ] ConstantPropagation.CustomClassesCanBePropagated (0 ms)
[----------] 1 test from ConstantPropagation (0 ms total)
Fixes #88613
Pull Request resolved: https://github.com/pytorch/pytorch/pull/119139
Approved by: https://github.com/jcaip
