The BuildTarget to build. (optional)
The output of the build is only compatible with the specific platform that it was built for, so you must produce
different builds to use the assets on different platforms.
If targetPlatform is not specified, e.g. it is 0, then the targetPlatform and subtarget fields will all be determined
from the current build settings.
It is strongly recommended to switch to the target platform prior to calling BuildPipeline.BuildContentDirectory,
to ensure that the Editor assemblies have been compiled to match the target platform and a domain reload has been performed.
BuildContentDirectory can build a different target platform than the one currently selected in the build settings, but it may not
work as expected because platform-specific conditional compilation will be applied and some build callbacks may not execute the expected code.
See the topic build-command-line in the Unity Manual for more details.
Additional resources: EditorUserBuildSettings.activeBuildTarget