Add new tests to verify behavior of the new byo DNS feature

Currently feature is in Tech preview

Author: sadasu

config/v1/techpreview.infrastructure.testsuite.yaml

@@ -696,5 +696,81 @@ tests:
         platform: AWS
         platformStatus:
           aws:
-            dnsConfig: {}
+            dnsConfig:
+              provider: ClusterProvided
           type: AWS
+  - name: Should be able to override the default Provider with a valid value
+    initial: |
+      apiVersion: config.openshift.io/v1
+      kind: Infrastructure
+      spec: 
+        platformSpec:
+          aws: {}
+          type: AWS
+    updated: |
+      apiVersion: config.openshift.io/v1
+      kind: Infrastructure
+      spec: 
+        platformSpec:
+          aws: {}
+          type: AWS
+      status:
+        platform: AWS
+        platformStatus:
+          aws: 
+            dnsConfig:
+              provider: UserProvided
+          type: AWS
+    expected: |
+      apiVersion: config.openshift.io/v1
+      kind: Infrastructure
+      spec: 
+        platformSpec:
+          aws: {}
+          type: AWS
+      status:
+        controlPlaneTopology: HighlyAvailable
+        cpuPartitioning: None
+        infrastructureTopology: HighlyAvailable
+        platform: AWS
+        platformStatus:
+          aws:
+            dnsConfig:
+              provider: UserProvided
+          type: AWS
+  - name: Should not allow changing the immutable Provider field
+    initial: |
+      apiVersion: config.openshift.io/v1
+      kind: Infrastructure
+      spec: 
+        platformSpec:
+          aws: {}
+          type: AWS
+      status:
+        controlPlaneTopology: HighlyAvailable
+        cpuPartitioning: None
+        infrastructureTopology: HighlyAvailable
+        platform: AWS
+        platformStatus:
+          aws:
+            dnsConfig:
+              provider: ClusterProvided
+          type: AWS
+    updated: |
+      apiVersion: config.openshift.io/v1
+      kind: Infrastructure
+      spec: 
+        platformSpec:
+          aws: {}
+          type: AWS
+      status:
+        controlPlaneTopology: HighlyAvailable
+        cpuPartitioning: None
+        infrastructureTopology: HighlyAvailable
+        platform: AWS
+        platformStatus:
+          aws:
+            dnsConfig:
+              provider: UserProvided
+          type: AWS
+    expectedStatusError: "status.platformStatus.aws.dnsConfig.provider: Invalid value: \"string\": type is immutable once set"