Add binary type for binary targets to add-target command.

[grantjbutler]

Updates the add-target subcommand to allow creating a target that references a remote or local binary artifact.

Motivation:

The add-target command currently accepts a set of arguments that make it seem like it should be able to create a .binaryTarget in the package's manifest. However, when trying to use the command in this way, you'll either get an error because of validation if trying to create a target for a remote binary artifact, or a regular source target will be created if trying to create a target for a local binary artifact. Issue #8277 has the full details.

Modifications:

This PR adds .binary as a new value for the TargetType enum (which is used for parsing the --type argument of the add-target command). This value gets mapped to TargetDescription.TargetKind.binary when actually creating the target in the manifest.

Result:

By specifying --type binary for the add-target command and providing a value for --url or --path, a .binaryTarget will be added to the package's manifest, with the appropriate configuration depending on if the binary artifact is sourced from a remote URL or a local path.

[plemarquand]

@swift-ci please test