No command palette option to sign in, and also no way to know that errors are occurring because you're not signed in.

**Describe the bug**
I had no idea I was able to sign in. Been dealing with this nonsense for over a year: #222

**To Reproduce**

1. Press Ctrl+Shift+P to open command palette
2. Type "github actions"
3. Observe that there is no sign in option.

There is an option called "focus on view" which does _then_ give you a sign in option.

**Expected behavior**

An option to sign in.

**Screenshots**

You can imagine.

**Extension Version**
`v0.27.0`

**Additional context**

Probably what happened (months ago)
- I open a yaml file.
- vscode tells me to install a recommended extension.
- it prompts me to log in so I can access my workflows.
- Of course I'm going to dismiss it immediately because I already have my yml file open and it's a popup. If it said "you will get spurious errors all over your yaml file" then I may have thought twice.

I feel like the error info on the "env" access should say "you need to be logged in" or something.

まず、「github actions」のコマンドパレットのフローと、env へのアクセス時に表示される検証エラーを追跡します。ユーザーが関連するコマンドパレットのコンテキストからサインインアクションを見つけられ、未認証時のエラーでサインインが必要であることが明確に説明されれば完了です。

索引モデルが issue の本文から書いたものです。