Modified the PowerShell completion script to replace the null-coalescing operator (`??` - a v7 feature) with a conditional statement compatible with PowerShell v5.1. The script now uses an if-else check for null descriptions in the language completion section.
* Add a --style=default option
* Added --style=default test and CHANGELOG entry
* Format CHANGELOG.md options with quotes
Co-authored-by: Martin Nordholts <enselic@gmail.com>
* Update help text for '--style'
* Make --style=default the default option
* Update style descriptions: "basic" -> "recommended"
* Add integration test for --style=default as default
* Update clap long help for --style