Add Mongo Proxy to Data Explorer (Standalone and Portal) (#1738)

* Mongo Proxy backend API

* merge main into current

* allow mongo proxy endpoints to be constants

* allow mongo proxy endpoints to be constants

* fix test

* check for allowed mongo proxy endpoint

* check for allowed mongo proxy endpoint

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Co-authored-by: Asier Isayas <aisayas@microsoft.com>

src/Contracts/ViewModels.ts

@@ -386,6 +386,7 @@ export interface DataExplorerInputsFrame {
   dnsSuffix?: string;
   serverId?: string;
   extensionEndpoint?: string;
+  mongoProxyEndpoint?: string;
   subscriptionType?: SubscriptionType;
   quotaId?: string;
   isTryCosmosDBSubscription?: boolean;