Invalid CRD types for ISM actions and a nil pointer fix (#788)

### Description

This fixes a few bugs found while testing the ISMPolicy custom
resources.

### Issues Resolved
_List any issues this PR will resolve, e.g. Closes [...]._ 

### Check List
- [x] Commits are signed per the DCO using --signoff 
- [x] Unittest added for the new/changed functionality and all unit
tests are successful
- [x] Customer-visible features documented
- [x] No linter warnings (`make lint`)

If CRDs are changed:
- [x] CRD YAMLs updated (`make manifests`) and also copied into the helm
chart
- [x] Changes to CRDs documented

Please refer to the [PR
guidelines](https://github.com/opensearch-project/opensearch-k8s-operator/blob/main/docs/developing.md#submitting-a-pr)
before submitting this pull request.

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and
signing off your commits, please check
[here](https://github.com/opensearch-project/OpenSearch/blob/main/CONTRIBUTING.md#developer-certificate-of-origin).

FYI @IshaGirdhar

---------

Signed-off-by: Casper Thygesen <cth@trifork.com>

charts/opensearch-operator/files/opensearch.opster.io_opensearchismpolicies.yaml

@@ -252,10 +252,10 @@ spec:
                             type: object
                           readOnly:
                             description: Sets a managed index to be read only.
-                            type: string
+                            type: object
                           readWrite:
                             description: Sets a managed index to be writeable.
-                            type: string
+                            type: object
                           replicaCount:
                             description: Sets the number of replicas to assign to
                               an index.
@@ -349,7 +349,8 @@ spec:
                             - snapshot
                             type: object
                           timeout:
-                            description: The timeout period for the action.
+                            description: The timeout period for the action. Accepts
+                              time units for minutes, hours, and days.
                             type: string
                         type: object
                       type: array

opensearch-operator/api/v1/opensearchism_types.go

@@ -109,9 +109,9 @@ type Action struct {
 	// Opens a managed index.
 	Open *Open `json:"open,omitempty"`
 	// Sets a managed index to be read only.
-	ReadOnly *string `json:"readOnly,omitempty"`
+	ReadOnly *ReadOnly `json:"readOnly,omitempty"`
 	// Sets a managed index to be writeable.
-	ReadWrite *string `json:"readWrite,omitempty"`
+	ReadWrite *ReadWrite `json:"readWrite,omitempty"`
 	// Sets the number of replicas to assign to an index.
 	ReplicaCount *ReplicaCount `json:"replicaCount,omitempty"`
 	// The retry configuration for the action.
@@ -124,7 +124,7 @@ type Action struct {
 	Shrink *Shrink `json:"shrink,omitempty"`
 	// Back up your cluster’s indexes and state
 	Snapshot *Snapshot `json:"snapshot,omitempty"`
-	// The timeout period for the action.
+	// The timeout period for the action. Accepts time units for minutes, hours, and days.
 	Timeout *string `json:"timeout,omitempty"`
 }
 
@@ -161,6 +161,10 @@ type Allocation struct {
 
 type Close struct{}
 
+type ReadOnly struct{}
+
+type ReadWrite struct{}
+
 type Delete struct{}
 
 type ForceMerge struct {

opensearch-operator/config/crd/bases/opensearch.opster.io_opensearchismpolicies.yaml

@@ -252,10 +252,10 @@ spec:
                             type: object
                           readOnly:
                             description: Sets a managed index to be read only.
-                            type: string
+                            type: object
                           readWrite:
                             description: Sets a managed index to be writeable.
-                            type: string
+                            type: object
                           replicaCount:
                             description: Sets the number of replicas to assign to
                               an index.
@@ -349,7 +349,8 @@ spec:
                             - snapshot
                             type: object
                           timeout:
-                            description: The timeout period for the action.
+                            description: The timeout period for the action. Accepts
+                              time units for minutes, hours, and days.
                             type: string
                         type: object
                       type: array

opensearch-operator/opensearch-gateway/requests/IsmPolicy.go

@@ -78,9 +78,9 @@ type Action struct {
 	// Opens a managed index.
 	Open *Open `json:"open,omitempty"`
 	// Sets a managed index to be read only.
-	ReadOnly *string `json:"read_only,omitempty"`
+	ReadOnly *ReadOnly `json:"read_only,omitempty"`
 	// Sets a managed index to be writeable.
-	ReadWrite *string `json:"read_write,omitempty"`
+	ReadWrite *ReadWrite `json:"read_write,omitempty"`
 	// Sets the number of replicas to assign to an index.
 	ReplicaCount *ReplicaCount `json:"replica_count,omitempty"`
 	// The retry configuration for the action.
@@ -130,6 +130,10 @@ type Allocation struct {
 
 type Close struct{}
 
+type ReadOnly struct{}
+
+type ReadWrite struct{}
+
 type Delete struct{}
 
 type ForceMerge struct {

opensearch-operator/pkg/reconcilers/ismpolicy.go

@@ -427,7 +427,9 @@ func (r *IsmPolicyReconciler) CreateISMPolicyRequest() (*requests.Policy, error)
 				}
 				var indexPri *requests.IndexPriority
 				if action.IndexPriority != nil {
-					indexPri.Priority = action.IndexPriority.Priority
+					indexPri = &requests.IndexPriority{
+						Priority: action.IndexPriority.Priority,
+					}
 				}
 				var snapshot *requests.Snapshot
 				if action.Snapshot != nil {
@@ -455,13 +457,13 @@ func (r *IsmPolicyReconciler) CreateISMPolicyRequest() (*requests.Policy, error)
 				if action.Timeout != nil {
 					timeOut = action.Timeout
 				}
-				var readWrite *string
+				var readWrite *requests.ReadWrite
 				if action.ReadWrite != nil {
-					readWrite = action.ReadWrite
+					readWrite = &requests.ReadWrite{}
 				}
-				var readOnly *string
+				var readOnly *requests.ReadOnly
 				if action.ReadOnly != nil {
-					readOnly = action.ReadOnly
+					readOnly = &requests.ReadOnly{}
 				}
 				actions = append(actions, requests.Action{
 					ReplicaCount:  replicaCount,