Add support for aria2 for faster downloads

[tahirmt]

It would be great to use aria2 to download Xcode faster when using fastlane

[jpsim]

FYI xcodes already does this. Personally I've switched to that tool to install and manage Xcode versions.

[tahirmt]

@jpsim I haven't used it because I added a lane in our fastlane setup to install Xcode if not there and with xcode-install I can use FASTLANE_SESSION so my CI machine can run it without requiring password

[rogerluan]

Adding this for future readers that would like to tackle this task: https://github.com/vineetchoudhary/Downloader-for-Apple-Developers this can be used as a guide on how to incorporate aria2 + xcode downloads (as well as xcodes aforementioned)