Repository: vscode
Issue: Incorrect behavior of granting access for the extension to existing authentication session using Manage Trusted Extensions functionality
Labels: bug,authentication

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- VS Code Version: 1.92.2
- OS Version: macOS 13.6.8

### Steps to Reproduce:

1. Create an extension with AuthenticationProvider, based on the sample: https://github.com/microsoft/vscode-extension-samples/blob/main/authenticationprovider-sample/src/authProvider.ts
2. Sign in, using credentials.
3. Go to Accounts -> extension's account -> Manage Trusted Extensions:
<img width="547" alt="image" src="https://github.com/user-attachments/assets/c155e961-6912-49f0-8c0f-5b414bbf1522">

4. Observe the list of trusted extensions for the selected account:
<img width="626" alt="image" src="https://github.com/user-attachments/assets/44b5776f-6e9f-434d-974c-1fbb7a074135">

5. Uncheck the extension from the list of trusted and press OK:
<img width="626" alt="image" src="https://github.com/user-attachments/assets/23f98eda-f22f-4fc5-acb1-7ed9cd4e5de2">

6. Observe an event is fired inside **vscode.authentication.onDidChangeSessions** subscription and method **await vscode.authentication.getSession(MyAuthenticationProvider.id, [], { createIfNone: false })** returns undefined:
<img width="526" alt="image" src="https://github.com/user-attachments/assets/baa226c3-7796-4611-8596-ac2cd22ee7f8">

7. Observe the option _Grant access to {Auth Provider} for {Extension}... (1)_ appeared under the Accounts menu:
<img width="421" alt="image" src="https://github.com/user-attachments/assets/60a71c21-b9de-47a1-9d8c-51476938cf28">

8. Select Accounts -> _Grant access to {Auth Provider} for {Extension}... (1)_
9. Observe a confirmation popup and press Allow:
<img width="262" alt="image" src="https://github.com/user-attachments/assets/ddb29194-98e2-4219-ab75-2fe97454ef7e">

10. Observe an event is fired inside **vscode.authentication.onDidChangeSessions** subscription and method **await vscode.authentication.getSession(MyAuthenticationProvider.id, [], { createIfNone: false })** returns session:
<img width="524" alt="image" src="https://github.com/user-attachments/assets/d24acc06-d44a-4a13-b699-e5ee6cb30faa">

11. Observe _Grant access to My Provider for My Extension... (1)_ is no longer exists in the Accounts menu:
<img width="377" alt="image" src="https://github.com/user-attachments/assets/05ae3d40-2ad1-4ef6-baff-ea9c56b9489c">

12. Repeat steps 3 - 7 for removing the extension from the list of trusted extensions again.
13. Navigate to Accounts -> extension's account -> Manage Trusted Extensions
14. Check the extension as trusted and press OK:
<img width="609" alt="image" src="https://github.com/user-attachments/assets/06cf8611-3325-44b0-b3c7-bd1673b181e9">

15. An event is fired inside **vscode.authentication.onDidChangeSessions** subscription and method **await vscode.authentication.getSession(MyAuthenticationProvider.id, [], { createIfNone: false })** returns session:
<img width="526" alt="image" src="https://github.com/user-attachments/assets/965a0457-4d10-4142-a281-36405b78a805">

### Actual Result:
 _Grant access to My Provider for My Extension... (1)_ is still available in the Accounts menu, even though access has been granted:
<img width="425" alt="image" src="https://github.com/user-attachments/assets/8d33f630-91d7-45dd-b562-88cb14d1791d">

### Expected Result:
- _Grant access to My Provider for My Extension... (1)_ should NOT be available in the Accounts menu.

### Consequences:
Since VS Code doesn’t provide a direct API to detect when the extension is checked/unchecked in the "Manage Trusted Extensions" dialog, it is impossible to work with authentication correctly.
While both, user account and _Grant access to My Provider for My Extension... (1)_ are available in the Accounts menu, it allows the possibility to sign in under two accounts, even if { supportsMultipleAccounts: false } was passed during registering the Authentication Provider, using
```
context.subscriptions.push(
    vscode.authentication.registerAuthenticationProvider(
      'myCustomProvider',
      'My Provider,
      new MyAuthenticationProvider (context.secrets),
      { supportsMultipleAccounts: false },
    ),
  );
```
To reproduce this behavior follow these steps:
1. Navigate to Accounts -> account -> Sign Out
2. Observe _Sign In with My Provider to use My Extension (1)_ appeared in the Accounts menu
3. Sign in, using another account
4. Observe new user account appeared in the Account menu.
5. Press _Grant access to My Provider for My Extension... (1)_
6. Observe both, previous and new account for the same extension presented in the Accounts menu.