List keys in SecretStorage (context.secret)

[DumpySquare]

in reference to;
Clear secrets when extension is uninstalled #123817

Need to be able to return all the keys in the secret store, so extensions can manage key lifecycle and clean up as needed. Without this, bloat is inevitable. This also brings the new secret store features a bit closer to the original keytar functionality

@TylerLeonhardt suggested a simple context.secret.keys() function to return all the keys available. This function is sufficient for this need

[gjsjohnmurray]

@TylerLeonhardt would you be open for a PR for this? The new keys() function would of course have to be behind a proposed API gate, though I hope it wouldn't take many iterations to get the green light for finalization.

[TylerLeonhardt]

Yes I would be open to that

[TylerLeonhardt]

Updates:

• The initial PR is merged in, thanks @gjsjohnmurray!
• It's been adopted in vscode.dev
• There is a PR out to adopt it in github.dev
• API Sync has approved it on one condition:
  Change the return type from string[] | undefined to just string[] so that we don't have to handle empty and undefined... Remove the undefined in the api #258295

[TylerLeonhardt]

Closing to track Test Plan Item creation but will re-open to track finalization.