Add a utility for completing platform strings.
Platforms offers completion for platform-strings. It provides a non-exhaustive
list of platforms to be used for completion. Platform-strings are based on
[runtime.GOOS] and [runtime.GOARCH], but with (optional) variants added. A
list of recognised os/arch combinations from the Go runtime can be obtained
through "go tool dist list".
Some noteworthy exclusions from this list:
- arm64 images ("windows/arm64", "windows/arm64/v8") do not yet exist for windows.
- we don't (yet) include `os-variant` for completion (as can be used for Windows images)
- we don't (yet) include platforms for which we don't build binaries, such as
BSD platforms (freebsd, netbsd, openbsd), android, macOS (darwin).
- we currently exclude architectures that may have unofficial builds,
but don't have wide adoption (and no support), such as loong64, mipsXXX,
ppc64 (non-le) to prevent confusion.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
ce1aebcc30