Add `basecamp-fizzy-cli` feature

[sebst]

Files:

src/(FeatureName)/devcontainer-feature.json
src/(FeatureName)/NOTES.md
src/(FeatureName)/install.sh (make sure to set executable bit)
test/(FeatureName)/test.sh
.github/workflows/test.yaml

Releases:

https://github.com/basecamp/fizzy-cli/releases

Test the installation process extensively before submitting
Watch for files in releases, naming structure, etc.
Test CLI output extensively before writing the test file.

For NOTES.md:
Link to the project that is installed by the feature
Short description of what it does
Installation method
Other notes