feat: introduce minimal chart values schema to catch structural changes

This introduces a minimal values.schema.json file to catch the
breaking structural changes made to the values.yaml file in the
related commits to this PR.

This will cause the 'helm template' or 'helm lint' commands
to throw errors and require consumers of the chart to fix
their values.yaml before deploying.

hack/charts/cluster-api-operator/values.schema.json

@@ -0,0 +1,56 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "type": "object",
+  "definitions": {
+    "nameNamespaceVersion": {
+      "type": "object",
+      "properties": {
+        "name": {
+          "type": "string"
+        },
+        "namespace": {
+          "type": "string"
+        },
+        "version": {
+          "type": "string"
+        }
+      },
+      "required": ["name"]
+    }
+  },
+  "properties": {
+    "core": {
+      "$ref": "#/definitions/nameNamespaceVersion"
+    },
+    "bootstrap": {
+      "type": "array",
+      "items": {
+        "$ref": "#/definitions/nameNamespaceVersion"
+      }
+    },
+    "controlPlane": {
+      "type": "array",
+      "items": {
+        "$ref": "#/definitions/nameNamespaceVersion"
+      }
+    },
+    "infrastructure": {
+      "type": "array",
+      "items": {
+        "$ref": "#/definitions/nameNamespaceVersion"
+      }
+    },
+    "addon": {
+      "type": "array",
+      "items": {
+        "$ref": "#/definitions/nameNamespaceVersion"
+      }
+    },
+    "ipam": {
+      "type": "array",
+      "items": {
+        "$ref": "#/definitions/nameNamespaceVersion"
+      }
+    }
+  }
+}