Add setContext notification for cody.serverEndpoint (#5918)

## Changes

I've added `cody.serverEndpoint` context variable, which on the clients
side is received through `window/didChangeContext` notification. We need
it on the jetbrains side in few places, e.g. when we are checking if
current account is a dotcom account.

I think it might be better idea to replace this with a dedicated
endpoint, but I'm not sure if `cody.activated` is currently used
anywhere?
@dominiccooney @sqs WDYT?



## Test plan

Full QA with sourcegraph/jetbrains#2382 is
needed.
It does not change anything on the Cody side.

vscode/src/services/AuthProvider.ts

@@ -16,7 +16,6 @@ import {
     clientCapabilities as getClientCapabilities,
     isAbortError,
     normalizeServerEndpointURL,
-    pluck,
     resolvedConfig as resolvedConfig_,
     setAuthStatusObservable as setAuthStatusObservable_,
     startWith,
@@ -111,10 +110,21 @@ class AuthProvider implements vscode.Disposable {
 
         // Keep context updated with auth status.
         this.subscriptions.push(
-            authStatus.pipe(pluck('authenticated')).subscribe(authenticated => {
+            authStatus.subscribe(authStatus => {
                 try {
-                    vscode.commands.executeCommand('setContext', 'cody.activated', authenticated)
-                } catch {}
+                    vscode.commands.executeCommand(
+                        'setContext',
+                        'cody.activated',
+                        authStatus.authenticated
+                    )
+                    vscode.commands.executeCommand(
+                        'setContext',
+                        'cody.serverEndpoint',
+                        authStatus.endpoint
+                    )
+                } catch (error) {
+                    logError('AuthProvider', 'Unexpected error while setting context', error)
+                }
             })
         )