Stop application freezes on macOS by moving data to MultiMC.app/Data

It appears that Minecraft Forge for Minecraft 1.17 will require setting
JVM arguments to operate, this is not currently possible with MultiMC's
meta.

Therefore, when Forge for 1.17 is released a solution will need to be
looked into.

This seems to have just been an inadvertent mistake when copy-pasting.
This commit just removes an annoying warning.

macOS seems to dislike changing files in the APPBUNDLE.app/Contents directory because it has to re-scan the directory every launch. As a result, large amounts of data there seems to cause freezes of MultiMC. Moving the default location outside of this directory, and thus the data, stops these freezes.
There is also a dialogue when the user first opens the app that asks them if they'd like to migrate their data folder, if they select yes it will move it, and if they select no it will not move it and allow them to move it later with an option in settings.

NOISSUE Use MiB suffix for Java memory options

This was a silly ommision I made.

NOISSUE Fix ATLauncher version selection combo box width