Add a mechanism to skip some tests that are not supported on firmware TPM

### Enhancement Proposal

There are some machines only have a firmware TPM, so some of the TPM-related test which are listed below will fail.
Could we consider adding either a resource job or a manifest to skip those tests that are not supported?

submission reference [here](https://certification.canonical.com/hardware/202004-27817/submission/453271/test-results/fail/)
`clevis-encrypt-tpm2/detect-ecc-capabilities`
`clevis-encrypt-tpm2/detect-rsa-capabilities`

Start by inspecting how Checkbox represents resource jobs or manifests, then trace the entries for clevis-encrypt-tpm2/detect-ecc-capabilities and detect-rsa-capabilities. The change is done when firmware TPM systems can skip these unsupported tests while supported TPM systems continue to run them.

Written by the indexing model from the issue text.