Add spec changes for subdomain routing on App Platform (#1005)

* Add spec changes for subdomain routing on App Platform

* Respond to feedback from @loosla:

- Wrap example.com in quotes
- Fix indentation for exact match (and prefix for consistency)
- Remove oneOf because it's not applicable

Author: Zach Eddy

specification/resources/apps/models/app_ingress_spec_rule_match.yml

@@ -1,7 +1,7 @@
 type: object
 properties:
   path:
-    $ref: app_ingress_spec_rule_string_match.yml
+    $ref: app_ingress_spec_rule_string_match_prefix.yml
+  authority:
+    $ref: app_ingress_spec_rule_string_match_exact.yml
 description: The match configuration for the rule.
-required:
-  - path

specification/resources/apps/models/app_ingress_spec_rule_string_match_exact.yml

@@ -0,0 +1,9 @@
+type: object
+properties:
+  exact:
+    type: string
+    maxLength: 256
+    example: "example.com"
+description: The authority to match on.
+required:
+  - exact

…s/app_ingress_spec_rule_string_match.yml …ngress_spec_rule_string_match_prefix.ymlspecification/resources/apps/models/app_ingress_spec_rule_string_match.yml renamed to specification/resources/apps/models/app_ingress_spec_rule_string_match_prefix.yml specification/resources/apps/models/app_ingress_spec_rule_string_match.yml renamed to specification/resources/apps/models/app_ingress_spec_rule_string_match_prefix.yml

@@ -7,4 +7,4 @@ properties:
     example: /api
 description: The path to match on.
 required:
-- prefix
+  - prefix