Missing support for easily adding swift packages to project

[garrik]

I have not found an api to perform all steps required to add a swift package to project.
When a swift package is added to an xcode project, it is modified as follows:

• a single entry is added to XCRemoteSwiftPackageReference section
• a single entry is added to PBXProject section
• an entry for each package product is added to XCSwiftPackageProductDependency section
• an entry for each package product is added to PBXFrameworksBuildPhase section, for given target
• an entry for each package product is added to PBXBuildFile section (the entry has productRef attribute in place of fileRef), for given target
• an entry for each package product is added to PBXNativeTarget section, for given target

As a side note, a file *.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved is also created, but I think this is out of scope.

I have modified mod-pbxproj and added an add_package function that performs the steps stated above. It can be used as follows:

from pbxproj import XcodeProject
    
# open the project
project = XcodeProject.load('DummyProject/DummyProject.xcodeproj/project.pbxproj')

project.add_package('https://github.com/SnapKit/SnapKit.git', 'SnapKit', 'DummyProject (iOS)', {
    "kind": "upToNextMajorVersion",
    "minimumVersion": "5.0.1"
})
project.add_package('https://github.com/openid/AppAuth-iOS.git', ['AppAuth','AppAuthCore'], 'DummyProject (iOS)', {
    "kind": "upToNextMajorVersion",
    "minimumVersion": "1.4.0"
})

project.save()

You can take a look the patch master...garrik:develop

This code just suits my needs but if you find it a viable solution, I would be happy to add tests, refactor, accept suggestion for improvement and contribute a pull request.
Regards

[kronenthaler]

Thanks @garrik, from a quick view it seems like a valuable addition, please create a PR and we can iterate there :)