Enable Cosmos DB Shell by default and clarify setup progress (#2593)

* Enable Cosmos DB Shell by default and clarify setup progress

Default enableCosmosDBShell to true while retaining explicit opt-out support. Add localized progress for SDK installation, shell installation, update checks, and connection with safe Bash quoting. Cover default visibility, overrides, and progress messages with regression tests.

Validation: npm run build:ci and 83 focused unit tests passed.

* Fix Index Advisor Playwright tooltip interference

src/Platform/Hosted/extractFeatures.ts

@@ -105,7 +105,7 @@ export function extractFeatures(given = new URLSearchParams(window.location.sear
     enableContainerCopy: "true" === get("enablecontainercopy"),
     enableRestoreContainer: "true" === get("enablerestorecontainer"),
     enableCloudShell: true,
-    enableCosmosDBShell: "true" === get("enablecosmosdbshell"),
+    enableCosmosDBShell: "true" === get("enablecosmosdbshell", "true"),
     mongoDisableNativeAuth: "true" === get("mongodisablenativeauth"),
   };
 }