feat: implement user schema management (#7416)

This PR adds the functionality to manage user schemas through the new user schema service.
It includes the possibility to create a basic JSON schema and also provides a way on defining permissions (read, write) for owner and self context with an annotation.

Further annotations for OIDC claims and SAML attribute mappings will follow.

A guide on how to create a schema and assign permissions has been started. It will be extended though out the process of implementing the schema and users based on those.

Note:
This feature is in an early stage and therefore not enabled by default. To test it out, please enable the UserSchema feature flag on your instance / system though the feature service.

internal/domain/schema/permission.schema.v1.json

@@ -0,0 +1,28 @@
+{
+  "$id": "urn:zitadel:schema:permission-schema:v1",
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$defs": {
+    "urn:zitadel:schema:property-permission": {
+      "oneOf": [
+        {
+          "type": "string",
+          "pattern": "^[rw]$"
+        }
+      ]
+    }
+  },
+  "properties": {
+    "urn:zitadel:schema:permission": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "owner": {
+          "$ref": "#/$defs/urn:zitadel:schema:property-permission"
+        },
+        "self": {
+          "$ref": "#/$defs/urn:zitadel:schema:property-permission"
+        }
+      }
+    }
+  }
+}