Install IPyKernel into all Python environments without the terminal

[DonJayamanne]

We found that installing ipykernel using shell doesn't work for a number of reasons (escaping paths, permissions in pwsh, etc).
& solved this for venvs by running the pip install by spawning a process.

We could try the same for all others and as a fall back, try the terminal.
This would work better in cases where conda isn't initialized in the vs code terminal.

TODO: Check whether this is still necessary as Rich may have already done this

[DonJayamanne]

Closing this as done & marking as bug to ensure this gets tested.

[DonJayamanne]

Steps to test this:

• Create a new conda environment
• Run a cell against this, and when prompted to intall ipykernel click yes
• Verify the installation does not happen in a Terminal

Repeat the same process for:

• virtual environment
• regular global python enviornment
• Poetry environment