Qualcomm AI Engine Direct - Enable HTP emulator test in x86 host (#4503)

Summary:
- Enable x64 runner
- Enable HTP emulator test on unit test
- Fix unexpected error message
- Fix multi-contexts UT's mismatching datatype issue
- Port x64 dequantize flow instead of using arm_neon intrinsics
- Fix EtDump flow on runner and unittest

Pull Request resolved: https://github.com/pytorch/executorch/pull/4503

Reviewed By: digantdesai

Differential Revision: D60598800

Pulled By: cccclai

fbshipit-source-id: bfb9df7948c3f64b2bd0e140836dfbd2d4655c0b