feat: display fancy icons on Windows Terminal

[innocenzi]

Proposed changes

This change allows to force the usage of the fancy icons via an environment variable, regardless of the current platform. This is because on Windows, the conhost shell does not support them by default (unless you change the font), but the Windows Terminal does. I couldn't find a way automatically detect whether or not the current terminal could handle these icons, so I opted for a flag.

On conhost.exe, some characters were not supported. Because of this, the platform is checked against win32 to determine if the usage of these characters is allowed.

This change updates that behavior by adding an additional check against the WT_SESSION environment variable, in order to allow these characters on the Windows Terminal, which supports them.

Sources:

• Consider setting environment variable when Terminal hosts cmd / powershell microsoft/terminal#840

Related:

• feat: display elegant spinner on Windows Terminal sindresorhus/elegant-spinner#5
• feat: display fancy symbols on Windows Terminal sindresorhus/log-symbols#24
• feat: display fancy figures on Windows Terminal sindresorhus/figures#34

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• I have read the CONTRIBUTING doc
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works.
• I have added necessary documentation (if appropriate)

[thetutlage]

Dope! Thanks for the PR 😄