Parse dump-pif result and reduce XCBuildSupport dependency

[giginet]

Use swift package dump-pif to construct PIF instead of the internal implementation of SwiftPM.

Using dump-pif command, we can reduce dependency and we can use stable specs.
Our final goal is to remove the XCBuildSupport dependency.

This PR introduces SwiftyJSON to manipulate PIFs. because it's tough to define a complete PIF using Codable. We only need a subset of PIF.

Instead, I concluded the JSON manipulation into the PIFKit target. ScipioKit can manipulate PIF in type-safe.