Prepare Mint Support

[Lutzifer]

To use a macro as binary, I followed a lot of the research at https://www.polpiella.dev/binary-swift-macros

The important parts are:

• in this repo: making the plugin an target executable (I have not yet tested this with mint):

• in the consuming repo: Including the mapping of macro binary to macro (via the project.yml and xcodegen) for all targets

(for us, the binary will be in the bin subfolder of iOS)

• in the consuming repo: removing the original macro from spm and removing all imports

• in the consuming repo: Including the macro definition(s) in a file (e.g. Sources/MacroDefinitions.swift) that is then directly imported to the project using the sources config of xcodegen. the definitions must be private.