Support nested `PermissionsClaimName`

Is your feature request related to a problem? Please describe.

Some JWT providers use nested claims format, like:

{
  "traits": {
    "temporal": [
      "one",
      "two",
      "three"
    ]
  }
}

Configuring PermissionsClaimName to traits.temporal would allow to use them without needing to write CustomClaimsMapper.

Describe the solution you'd like
Ability to specify JSONPath for PermissionsClaimName.

Describe alternatives you've considered
Creating custom ClaimsMapper as per https://docs.temporal.io/self-hosted-guide/security#authorization

Start by tracing how PermissionsClaimName is read and how the documented CustomClaimsMapper authorization path handles claims. Verify that configuring traits.temporal resolves the nested values without a custom mapper, and add coverage for the nested JSON claim format.