Add entitlement option to Satellite cluster/workerpool create

[TwoDCube]

We shipped a new feature to allow setting the entitlement of worker pools for Satellite Clusters. This PR is to make this change available in Terraform as well. The change in the API is available in all production regions.

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Relates OR Closes #0000

Output from acceptance testing:

% make testacc TEST='./ibm/service/satellite/...' TESTARGS='-run=TestAccSatelliteCluster_Entitlement'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./ibm/service/satellite/... -v -run=TestAccSatelliteCluster_Entitlement -timeout 700m
[...]
=== RUN   TestAccSatelliteCluster_Entitlement
--- PASS: TestAccSatelliteCluster_Entitlement (6586.04s)
PASS
ok      github.com/IBM-Cloud/terraform-provider-ibm/ibm/service/satellite       6587.124s

% make testacc TEST='./ibm/service/satellite/...' TESTARGS='-run=TestAccSatelliteClusterWorkerPool_Entitlement'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./ibm/service/satellite/... -v -run=TestAccSatelliteClusterWorkerPool_Entitlement -timeout 700m
[...]
=== RUN   TestAccSatelliteClusterWorkerPool_Entitlement
--- PASS: TestAccSatelliteClusterWorkerPool_Entitlement (5445.76s)
PASS
ok      github.com/IBM-Cloud/terraform-provider-ibm/ibm/service/satellite       5446.898s

[TwoDCube]

This was copied from here, as this option has the exact same behavior as with vpc clusters.

terraform-provider-ibm/website/docs/r/container_vpc_cluster.html.markdown

Line 176 in ee5af15

- `entitlement` - (Optional, String) Entitlement reduces additional OCP Licence cost in OpenShift clusters. Use Cloud Pak with OCP Licence entitlement to create the OpenShift cluster. **Note** <ul><li> It is set only when the first time creation of the cluster, further modifications are not impacted. </li></ul> <ul><li> Set this argument to `cloud_pak` only if you use the cluster with a Cloud Pak that has an OpenShift entitlement.</li></ul>.

Also, the docs for satellite_cluster_workerpool already included the entitlement option, even though the code did not support it.