Improve display names of interpreters in the list and status bar

The prefix 'packaged by conda-forge` should not be added to some of the interpreters. As this belongs to the root interpreters

@brettcannon @qubitron We’ll need to go come up with a set of rules for the display names of:

• Conda, virtual, venv, and other environments.

• Create new api to retrieve interpreter details with the ability to cache it #1569

[brettcannon]

If we can’t tell the difference between miniconda and Anaconda installs then I say go with the latter for consistency.

[DonJayamanne]

@qubitron Ref https://github.com/Microsoft/vscode-python/issues/1362 You’ve suggested we display the name of the virtual environment instead of venv. The format we agreed on is:

Python 2.7.14 32-bit (base: conda)
Python 2.7.14 32-bit (env-01: conda)
Python 3.5.1 64-bit (env-02: conda)
Python 2.7.14 32-bit (v01: pipenv)
Python 3.5.1 32-bit (v02: pipenv)
Python 3.5.1 32-bit (v03: pipenv)
Python 3.5.1 32-bit (v03: pyenv)
Python 3.6.1 32-bit (v03: venv)
Python 3.5.1 32-bit (myenv2: virtualenv)

Looking at Python 3.6.1 32-bit (v03: venv), v03 is the folder name. So I believe this addresses issue #1362