Parsing .swiftinterface form xcframework

[rehsals]

Problem
Issue: #87
Our project is really big so we decided to use it's dependencies as binary XCFrameworks.
The problem is to mock types declared in modules from such binary frameworks which we manage with CocoaPods.
The idea to work this limitation around was to scan .swiftinterface file inside the xcframework.

Line of thought
At first I considered I could use sources key to set this up. But sources is mutually exclusive
with project which is an issue in our case. I gave it a try to make sources usable along with project
but it didn't work quite well. The thing is we need to use module name to namespace types in mocks. The case of matching
type names is not so rare. So sources was not entirely working. Another consideration was to scan .xcodeproj to find a path
to xcframework and add it to sources list. But CocoaPods makes target so placeholder-ish that there is no way that I could find
to extract that path.

Proposed solution
Finally I introduced optional key xcframework to configuration.

project:
  - file: "Pods/Pods.xcodeproj"
    target:
      - name: "Alamofire"
        xcframework: "Pods/Alamofire/Alamofire.xcframework"

This path is added to target and gets scaned. Some messy fiddling with paths inside .xcframework file could be avoided but
for now it just works. Also the xcframework key could be made an array (not done yet)

This Pull Request might not be the the right way to do it, but might as well be the starting point for a discussion.
I am sure there is a better way to achieve this.

[krzysztofzablocki]

this looks good to me, it solves the problem at hand and the code doesn't look bad or complicated.

Let's just add support for the array case 🔥

[rehsals]

Great! Thanks. Then I'll spend some time making this PR mergeable

[rehsals]

So I guess the PR is ready for review

[krzysztofzablocki]

thanks!