VS Code: Implement Single account UI and interactions (behind FF)
Problem to solve
When introducing the "Single Account per Window" feature, we need to let user know which account they currently use and we need to let them select an account when there are multiple available.
Proposal
Implement the UX interactions and the "backend" manager and modules to support the new UX.
The implementation will be behind a Feature Flag.
The POC for this is here VS Code - Single User per Window POC (!2135 - closed). You can see all the interactions there.
The POC explains the changes in detail:
- Status bar item (the original purpose of this issue)
- Welcome screen (shown when there are multiple accounts available)
- Commands, quick picks and interactions to work with multiple accounts
Further details
This issue must be done before we implement #1377 (closed)
Original description
### Problem to solveIf the user has multiple accounts set up, it's not obvious, which one is used in the current workspace (window).
Proposal
If there are multiple accounts, show the active account in a status bar item.
Further details
[VS Code] Only support single account per works... (#1377 - closed) must be done first
