Epic: Improve BATS tests

[jandubois]

• Make BATS work with npm dev setup on Windows #4542
• Create BATS tests for BATS helper functions #5130
• Write BATS best practices and style guide document
• Write unit tests for profile.bash helper functions
• Document all BATS tests
• Document all environment variables used to configure BATS
• Run BATS on Windows in Github Actions
• Run BATS on Linux in Github Actions