feat: remove CompartmentId mandatory from ocicluster_types

[joekr]

What this PR does / why we need it:
CompartmentId is still mandatory, but the admission webhook is now handling the validation.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #66

[joekr]

unit tests

?       github.com/oracle/cluster-api-provider-oci      [no test files]
ok      github.com/oracle/cluster-api-provider-oci/api/v1beta1  0.247s  coverage: 7.8% of statements
?       github.com/oracle/cluster-api-provider-oci/cloud/config [no test files]
ok      github.com/oracle/cluster-api-provider-oci/cloud/ociutil        0.741s  coverage: 30.3% of statements
ok      github.com/oracle/cluster-api-provider-oci/cloud/scope  175.824s        coverage: 81.9% of statements
?       github.com/oracle/cluster-api-provider-oci/cloud/scope/mocks    [no test files]
?       github.com/oracle/cluster-api-provider-oci/cloud/services/compute       [no test files]
?       github.com/oracle/cluster-api-provider-oci/cloud/services/compute/mock_compute  [no test files]
?       github.com/oracle/cluster-api-provider-oci/cloud/services/identity      [no test files]
?       github.com/oracle/cluster-api-provider-oci/cloud/services/identity/mock_identity        [no test files]
?       github.com/oracle/cluster-api-provider-oci/cloud/services/networkloadbalancer   [no test files]
?       github.com/oracle/cluster-api-provider-oci/cloud/services/networkloadbalancer/mock_nlb  [no test files]
?       github.com/oracle/cluster-api-provider-oci/cloud/services/vcn   [no test files]
?       github.com/oracle/cluster-api-provider-oci/cloud/services/vcn/mock_vcn  [no test files]
ok      github.com/oracle/cluster-api-provider-oci/controllers  26.485s coverage: 70.7% of statements

e2e tests

Summarizing 1 Failure:

[Fail] Workload cluster creation [It] Cloud Provider OCI testing [PRBlocking]
/home/ubuntu/projects/cluster-api-provider-oci/test/e2e/ccm_helpers.go:83

Ran 5 of 21 Specs in 1942.343 seconds
FAIL! -- 4 Passed | 1 Failed | 0 Pending | 16 Skipped

running CCM in SYD

• [SLOW TEST:1064.703 seconds]
Workload cluster creation
/home/ubuntu/projects/cluster-api-provider-oci/test/e2e/cluster_test.go:49
  Cloud Provider OCI testing [PRBlocking]
  /home/ubuntu/projects/cluster-api-provider-oci/test/e2e/cluster_test.go:201
------------------------------
STEP: Tearing down the management cluster


Ran 1 of 21 Specs in 1149.704 seconds
SUCCESS! -- 1 Passed | 0 Failed | 0 Pending | 20 Skipped