feat(cloud9): always add default region #2717

Problem:
On Cloud9, changing credentials is uncommon, while _new_ environments
_are_ common. Showing a prompt to ask about adding a region to AWS
Explorer is noisy.

Solution:
On Cloud9, add the credentials-default region to AWS Explorer without
prompting.

Author: justinmk3

src/awsexplorer/defaultRegion.ts

@@ -11,7 +11,7 @@ import { AwsContext } from '../shared/awsContext'
 import * as localizedText from '../shared/localizedText'
 import { createQuickPick, promptUser } from '../shared/ui/picker'
 import { AwsExplorer } from './awsExplorer'
-import { getIdeProperties } from '../shared/extensionUtilities'
+import { getIdeProperties, isCloud9 } from '../shared/extensionUtilities'
 import { PromptSettings } from '../shared/settings'
 
 class RegionMissingUI {
@@ -35,6 +35,12 @@ export async function checkExplorerForDefaultRegion(
         return
     }
 
+    if (isCloud9()) {
+        await awsContext.addExplorerRegion(profileRegion)
+        awsExplorer.refresh()
+        return
+    }
+
     const shouldPrompt = await PromptSettings.instance.isPromptEnabled('regionAddAutomatically')
     if (!shouldPrompt) {
         return