Native XCode project generator plugin

[JX-Master]

Is your feature request related to a problem? Please describe.

The current version of xmake (2.8.8) does not support XCode project generation directly, it generates XCode project files by translating xmake scripts to CMake scripts, then uses CMake genrator to generate XCode project files. In practice, I found at least two problems caused by this translation process:

1. All custom building functions used in xmake scripts (like before_build, after_build, before_install, after_install, etc) will not be called when performing building actions in XCode, since they are lua functions and cannot be processed by CMake building system.
2. For some reasons, if we need to change the building options (options added by target:add_options) in xmake, we don't get these option changes applied in XCode projects until we delete all CMake/XCode files and regenerate them from scrach (simply regenerating XCode project files by xmake project -k xcode won't take effect if we don't delete all existing CMake and XCode files).

These problems can be solved by implementing a native XCode project generator, just like we have already done for Visual Studio (vsxmake2019). As the documentation says:

After we have time, we will re-implement each more complete xcode output plugin by ourselves, and welcome everyone to contribute.

I wonder if we currently have any plan on implementing a native XCode project generator, and if not, this issue can be used to track this feature if somebody has time to development such generator later.

Describe the solution you'd like

We want a native XCode project generator that generates XCode project files directly from xmake.lua project scripts. When performing building, installing and cleaning actions in XCode, this project file will call xmake to perform real building tasks, so that all custom building functions can be used, and changes to xmake options will take effect immediately in XCode projects.

Describe alternatives you've considered

No response

Additional context

No response