skip unimplemented error; update workflow

[Yejing-Lai]

skip logic:

1. Builder name does not exist or is not implemented, then skip.
2. Use “skipif(CPU)” to skip some test cases on the CPU device.

[delock]

Overall comments: we should avoid compare backend name against certain accelerator name. Instead, check for certain features that are required by the case. These tests that check for not implemented is a good example. Its reasonable to skip a UT if feature are not implemented, but not reasonable to skip just because it cannot pass for certain accelerator.