When VS Code is launched from a terminal with an activated environment, select it

[brettcannon]

For both virtual and conda environments, if you launch VS Code from an activated environment, we should pick that up and automatically select that environment for the user if no environment had been previously selected.

One open question, though, is what to do if you had an environment previously selected? Do we:

1. Ignore the one you launched VS Code under?
2. Automatically select the activated one?
3. Prompt to see whether you want to keep your previously selected environment or switch to the activated one?

[paulacamargo25]

The team discuss this and we decided that we will select the activated environment if there is no environment explicitly selected by User.