rootDir configuration (to potentially support mono repos)

[lukethacoder]

Is your feature request related to a problem? Please describe.

Attempting to use this extension in a monorepo does not work as expected due to the plugin expecting the SFDX Project to be the root directory.

Describe the solution you'd like

Add a rootDir plugin config option to flag which folder should be used as the SFDX project root

Describe alternatives you've considered

Can open the individual folder in different VS Code instance, but I would rather stay within one instance of the mono repo.

Additional context
Add any other context or screenshots about the feature request here.