Support conda environement for bira theme

Description

Support for the showing the conda environment for the bira theme. This will prioritise the virtualenv prompt.

Motivation and Context

I usually got confused whether conda is activated or not, then found that it is in fact activated but theme doesn't handle CONDA_DEFAULT_ENV variable.

How Has This Been Tested?

Locally, sourcing the new script with new changes and activating the environment

Screenshots (if appropriate):

Types of changes

[x] Bug fix (non-breaking change which fixes an issue)
[x] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

[x] My code follows the code style of this project.
[x] If my change requires a change to the documentation, I have updated the documentation accordingly.
[x] I have read the CONTRIBUTING document.
[x] If I have added a new file, I also added it to clean_files.txt and formatted it using lint_clean_files.sh.
[x] I have added tests to cover my changes, and all the new and existing tests pass.

Bash-it / bash-it

Support conda environement for bira theme #2256