Provide a simple way to share Qt Creator's settings amongst machines

With clang tidy and clazy, for example, it shouldn't be necessary to customize each Creator instance by hand, but rather it should be possible to e.g.:

• Export the settings and then import them from other Creator instances, or
• Have the settings stored in the Qt Account and allow the user to sync them across each Creator instance.

This applies to all settings: theme, snippets, shortcuts, etc.

This can be done manually already by copying and pasting the .ini file, but that's platform-dependent and not very nice.

If this is out of scope, then there should be documentation for how to manually share settings like the clang tidy configuration, etc.