New version apis documentation (Azure#13928)

* New version apis documentation

* Fix Tests

* fix tests

* remove tag to v2019-12-01 as it is not in use

* Fix tests

* Fix version and readme.md

* Align the title to Marketplace RP Service and add default response to v2019-12-01

* remove the default response on version 2019-12-01

* Fix Errors

* Fix errors

* remove 2019 api version

* Revert "remove 2019 api version"

This reverts commit effa0cc.

* Adding v2019 back

* remove v2019

* align with master latest changes

* Fix conflict

* fix conflict

* Fix tests

* adding more apis

* Add API: collectionsSubscriptionsMapping

* Adding api: query offers

* Change transferOffers response body to retrieve which on collections the operation succeeded or failed

Author: MiriBerezin

specification/marketplace/resource-manager/Microsoft.Marketplace/stable/2019-12-01/Marketplace.json

@@ -2,7 +2,7 @@
   "swagger": "2.0",
   "info": {
     "version": "2020-01-01",
-    "title": "MarketplaceManagementClient",
+    "title": "Marketplace RP Service",
     "description": "REST APIs for Azure Marketplace"
   },
   "host": "management.azure.com",

specification/marketplace/resource-manager/Microsoft.Marketplace/stable/2019-12-01/examples/GetPrivateStoreClient.json

@@ -2,7 +2,7 @@
   "swagger": "2.0",
   "info": {
     "version": "2020-12-01",
-    "title": "MarketplaceManagementClient",
+    "title": "Marketplace RP Service",
     "description": "REST APIs for Azure Marketplace"
   },
   "host": "management.azure.com",