fix(ocm): `publicKey` can be disabled so capabilities do not match

When the public key feature is disabled null is returned for
`publicKey`. So in this case we need to adjust the capabilities
and return type of `jsonSerialize()`.

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

apps/cloud_federation_api/lib/Capabilities.php

@@ -38,7 +38,7 @@ class Capabilities implements ICapability {
 	 *     	   apiVersion: '1.0-proposal1',
 	 *         enabled: bool,
 	 *         endPoint: string,
-	 *         publicKey: array{
+	 *         publicKey?: array{
 	 *             keyId: string,
 	 *             publicKeyPem: string,
 	 *         },

apps/cloud_federation_api/openapi.json

@@ -46,7 +46,6 @@
                             "apiVersion",
                             "enabled",
                             "endPoint",
-                            "publicKey",
                             "resourceTypes",
                             "version"
                         ],

lib/private/OCM/Model/OCMProvider.php

@@ -213,7 +213,7 @@ class OCMProvider implements IOCMProvider {
 	 *      enabled: bool,
 	 *      apiVersion: '1.0-proposal1',
 	 *      endPoint: string,
-	 *      publicKey: array{
+	 *      publicKey?: array{
 	 *          keyId: string,
 	 *          publicKeyPem: string
 	 *      },
@@ -236,7 +236,7 @@ class OCMProvider implements IOCMProvider {
 			'apiVersion' => '1.0-proposal1', // deprecated, but keep it to stay compatible with old version
 			'version' => $this->getApiVersion(), // informative but real version
 			'endPoint' => $this->getEndPoint(),
-			'publicKey' => $this->getSignatory()->jsonSerialize(),
+			'publicKey' => $this->getSignatory()?->jsonSerialize(),
 			'resourceTypes' => $resourceTypes
 		];
 	}

lib/public/OCM/IOCMProvider.php

@@ -151,7 +151,7 @@ interface IOCMProvider extends JsonSerializable {
 	 *     enabled: bool,
 	 *     apiVersion: '1.0-proposal1',
 	 *     endPoint: string,
-	 *     publicKey: array{
+	 *     publicKey?: array{
 	 *         keyId: string,
 	 *         publicKeyPem: string
 	 *	   },