Install dependencies for users

[LukeSlev]

Description:

This PR makes it so that users are prompted to have the python dependencies installed for them

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

Limitations:

We don't check if they need the pop up, we always pop up the option as running the install command when you already have the packages doesn't error out

Testing:

• should be able to install all python dependencies through the pop up

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

[markAtMicrosoft]

We should update the https://github.com/microsoft/vscode-python-embedded/blob/dev/docs/developers-setup.md file to match the changes for dependencies. Maybe should tell them before they type all those pip commands in that the extension will do it for them on execution.

[jonathanwangg]

Conflicts