Select suitable configs for auto-generated schemes

[giginet]

Motivation and Context

In a situation, there is the following project definition.

name: MyApp
configs:
  Beta: debug
  Debug: debug
  Production: release
  Release: release
targets:
  MyFramework:
    type: framework
    platform: iOS
    sources: MyFramework
    scheme:
      testTargets:
        - MyFrameworkTests
  MyFrameworkTests:
    type: bundle.unit-test
    platform: iOS
    sources: MyFrameworkTests

Auto-generated schemes select Beta as debug config and Production as release config.
Because there are prior ones by alphabetical order.

However, we'll expect they select Debug and Release configuration.
This behavior seems to be ambigious.

Description

This PR make to use Debug and Release piror to first ones.

And I added test cases for SchemeGenerator.

Before	After

[yonaskolb]

Thanks @giginet!

[philippelatulippe]

Hi! Is there a way to disable this change, or to explicitly state which build configuration I want to use for a target's generated change? My "Release" targets used the build configuration "AdHoc", but with this change they suddenly started using the wrong build configuration.

I understand that it's just by luck of alphabetical sorting that it worked in the past, but now I can't find a way to set the build configuration of the convenience target scheme.

[giginet]

@philippelatulippe Hi ✋

I think you're better to specify configurations expressly on project scheme section.
https://github.com/yonaskolb/XcodeGen/blob/master/Docs/ProjectSpec.md#scheme

schemes:
  Release:
    build:
      targets:
        Release: all
    archive:
      config: AdHoc

[giginet]

Your previous usage may be a bit fragile.