Add PathARNExtractor for kms_key_id to rds cluster

[turkenf]

Description of your changes

Adds the PathARNExtractor for kms_key_id to the rds cluster resource

Fixes: #1523

I have:

• Read and followed Crossplane's contribution process.
• Run make reviewable to ensure this PR is ready for review.
• Added backport release-x.y labels to auto-backport this PR if necessary.

How has this code been tested

Tested with uptest (https://github.com/crossplane-contrib/provider-upjet-aws/actions/runs/11456655642) and manually:

  conditions:
  - lastTransitionTime: "2024-10-22T08:42:00Z"
    reason: ReconcileSuccess
    status: "True"
    type: Synced
  - lastTransitionTime: "2024-10-22T08:42:55Z"
    reason: Available
    status: "True"
    type: Ready
  - lastTransitionTime: "2024-10-22T08:42:53Z"
    reason: Success
    status: "True"
    type: LastAsyncOperation
  - lastTransitionTime: "2024-10-22T08:44:24Z"
    reason: UpToDate
    status: "True"
    type: Test

[turkenf]

/test-examples="examples/rds/v1beta1/cluster-with-kmskey.yaml"

[erhancagirici]

thanks @turkenf, LGTM