UX: Inability to switch between Microsoft and GitHub accounts without first turning off Settings Sync is highly unintuitive

### Description

The current account switching flow in VS Code is extremely unintuitive and provides no clear affordance for users who want to switch between a GitHub account and a Microsoft account.

### Steps to Reproduce

Initially sign in to VS Code and turn on Settings Sync using a GitHub account.

Later, decide to switch to a Microsoft account for synchronization.

Click the Accounts icon in the bottom-left corner and select "Sign Out".

Click "Sign in to Sync Settings" again.

### Actual Result

VS Code automatically redirects to the previously used GitHub OAuth flow without ever presenting an option to choose a different account provider (Microsoft). The user is effectively locked into the first account type they chose.

### Expected Result

After signing out, users should be presented with a clear choice of which account provider (e.g., "Sign in with GitHub" or "Sign in with Microsoft") to use for the new session. The current requirement to know and execute the undocumented step of "Settings Sync: Turn Off" via the Command Palette (Ctrl+Shift+P) is a significant UX failure. A simple "Switch Account" option in the Accounts menu would be a much more intuitive solution.

### Workaround Found (Undocumented)

The only way to trigger the account provider selection is to:

Open Command Palette (Ctrl+Shift+P).

Run Settings Sync: Turn Off.

Click the Accounts icon again and select "Sign in to Sync Settings".

Only then does the UI present the option to choose between GitHub and Microsoft.

### Suggested Fix

Add a "Switch Account" or "Change Account Provider" option directly in the Accounts menu that does not require turning sync off.

Alternatively, always show the provider selection screen upon signing out and attempting to sign back in.

### Related Issues

This appears to be a recurring pain point for many users, as evidenced by similar reports:

#192969: "Settings Sync" fails to switch from Github account to Microsoft account

#198868: Not able to delete/switch account (sign out Microsoft and then sign in GitHub)

#213851: Can't sync settings to Microsoft account after trying Github one

#213714: Cannot log into a different github account after signing into one

### VS Code Version

ALL Version

### OS Version

ALL OS