Adds provider detection for LibKrun in `pkg/provider/platform_darwin.go`.
Changes the macOS version check to 13 instead of 11, and now uses the `semver`
package to verify current version.
Signed-off-by: Jake Correnti <jakecorrenti+github@proton.me>
Extends the `pkg/machine/provider` package to add an API which includes
provider detection based on the host operating system.
Signed-off-by: Jake Correnti <jakecorrenti+github@proton.me>
