MRU list in enhanced kernel picker

[sharoncxu]

Manage a list of previous connections and group them by kernel type/language for the user. All non-standard connections will be placed under the "Other" category.

User Scenario The user will first be shown a list of kernels:

After selecting one, they will be shown a list of all previously used kernels/connections:

The flow for adding and removing items from the MRU list should be roughly as follows:

• [ ] Mark the --connection-string parameter (and others as appropriate) as "sensitive" and when a cell containing hard-coded values for this parameter is run, do not add to the MRU list.
• [ ] Add a warning message in the cell output when users have a hardcoded value in a "sensitive" parameter, informing them it will not appear in the MRU list and suggest them to use an @input instead.
• [ ] Create public API to allow users to mark custom parameters as "sensitive".
• [ ] Instructions on how to delete a secret from the database with the PowerShell code should be displayed in the cell output. (This is currently the case with a single @input but not with multiple.) If the user has more than one @input, the message should only be displayed once along with instructions to replace the value name with the correct one, e.g. instead of Remove-Secret -Name "xyz" -Vault DotnetInteractive it should suggest something more generic.
• [ ] Include up to 5 connections in the MRU list. The most recently-used connection will bump the previously used one down the list
• [ ] Include a Delete button in the quickpick UI to allow the user to remove connections from the list.
• [ ] If VS Code allows two buttons, add a button to Pin the connection in the list.

[AbhitejJohn]

We'd also want to consider running the accessibility insights tool for the overall workflow. Even though the controls themselves might be standard, the integration sometimes surfaces interesting issues (keyboard navigation for instance).