Add support for scheme pre-actions and post-actions

[kastiglione]

Add support for scheme pre-actions and post-actions

This pull request adds preActions and postActions to each of the scheme action types. For example:

schemes:
  Foo:
    build:
      preActions:
        - name: Prepare Build
          script: echo Preparing for Build

✅ Check List ✅

• Add tests
• Add some actions to the scheme spec loading test
• Add a custom scheme with actions to the test fixture
• Add support for inheriting build settings (see environmentBuildable)
• Update ProjectSpec.md
• Check whether script needs to be escaped

This change requires tuist/XcodeProj#217.

[kastiglione]

@yonaskolb To build XcodeGen with the latest HEAD of xcproj, I had to make the changes in 1fe2e96. Feel free to cherrypick it into #227.

[yonaskolb]

@kastiglione, #227 is merged

[yonaskolb]

Do you want to add pre and post actions to TargetScheme as well? It would just apply them to all the different actions in the Scheme init here https://github.com/yonaskolb/XcodeGen/blob/master/Sources/XcodeGenKit/ProjectGenerator.swift#L178

[kastiglione]

I don't need that functionality for my work. Do you think it will be common enough for people to have a script they want executed before/after every build, run, test, profile, and archive? I don't know the answer to this, but I can check, are these scripts called with arguments or environment variables that indicate which action (build/run/test/etc) is being invoked? If not, then I would say not to add it.

[kastiglione]

I just checked, the pre/post action scripts don't have any arguments or environment variables that tell which type of action (build/run/test/etc) triggered the script.

[kastiglione]

Thanks for the review and approval. I plan to do the changes mentioned in the todo checklist. That can be here or a follow up.

[yonaskolb]

They can be done here 👍

[kastiglione]

Ready to merge, pending review of updates.

[yonaskolb]

Looks great @kastiglione, thanks!
If you have time to add some actions to the scheme spec loading test, and add a custom scheme with actions to the test fixture that would be great

[kastiglione]

Tests added.

[yonaskolb]

Nice! Just the updated test project needs to be committed after running the tests. (The tests won't fail automatically with scheme changes at the moment due to #202)

[yonaskolb]

As a note for the future, tests here aren't strictly required as the tests will fail if the generated project changes. Someone just added some more explicit checks afterwards above once. No harm in having this here though 👍

[yonaskolb]

I'll do it in master 👍