Enable parsing incremental parsing by utilizing `pluginGeneratedResources`

[dfed]

When SafeDI was written, it was not possible for a Swift Package Plugin to depend on the output of a plugin run in a dependent module. In Swift 6, this is now possible by using the pluginGeneratedResources property on SwiftSourceModuleTarget.

This feature will enable extremely large codebases to adopt SafeDI without experiencing performance impacts or building execution tooling outside of SPM.