Add support for file header template

[olejnjak]

Short description 📝

As working in team various file header templates might apply. This is done by using IDETemplateMacros.plist inside xcodeproj. This plist might be shared so located under xcshareddata and also user-specific. This PR currently addresses shared data.

Currently this PR is a draft to discuss the implementation, tests and docs will be added afterwards.

As it might be desired to add also user-specific macros, I implemented new ProjectMapper that is responsible for created the above mentioned plist. If later the Config is extended with user-specific macros then the IDETemplateMacrosProjectMapper can be easily updated to create more plists.

Checklist ✅

• The code architecture and patterns are consistent with the rest of the codebase.
• The changes have been tested following the documented guidelines.
• The CHANGELOG.md has been updated to reflect the changes. In case of a breaking change, it's been flagged as such.
• In case the PR introduces changes that affect users, the documentation has been updated.

[kwridan]

Nice work @olejnjak thanks for submitting this!

I like the overall approach and +1 for using a mapper for this as it fits quite nicely!

Some thoughts:

• There's talk of deprecating Config.generationOptions :/ Deprecating global project attributes in favour of helpers #2429 in favour of per Manifest configuration. Co-incidentally the same topic was brought up here Per-Project Resource Accessors #2564 too regarding how to define this per project.

• If I'm not mistaken, header templates can be applied at the workspace level too which automatically get applied to all projects with it

  • This would mean the template header is only ever created once per workspace rather than for every individual project, we can convert the mapper to a WorkspaceMapper and apply the same logic you have already applied here such that the plist is placed in <WorkspaceName>.xcworkspace/xcshareddata/IDETemplateMacros.plist
  • If we proceed with discussions above regarding deprecating config, perhaps having this at the workspace level could be a bit easier to adopt globally rather than per-project (thought I still see the value of the config defined approach so not sure how to proceed with this one :/ )

• Worth adding a fixture to show-case this in the various forms :)

[olejnjak]

Should be ready right now with following changes:

• IDETemplateMacrosMapper now supports not just project mapping, but also workspace mapping as it should basically do the same job regarding projects and workspaces (add a plist into its shared data)
• when creating IDETemplateMacros with template string that should be used, various "normalizations" are performed to easily achieve desired state
  • remove extra comment slashes if appropriate as they are added automatically by Xcode
  • add extra leading space if template doesn't start with comment slashes and doesn't start with whitespace
  • remove extra traling space as it is automatically added by Xcode

[kwridan]

Awesome work @olejnjak - thanks for all the updates, it's looking great!