(182+) Auto-focus on input in settings

[fwdekker]

Estimated implementation date: unknown
Adapted from checklist in #209.

When a Randomness settings dialog is opened, one of the inputs should be focused on. This should be possible by implementing #getPreferredFocusedComponent in the Components, which is available starting at build 182.

Unfortunately, it appears that #getPreferredFocusedComponent is not used inside settings dialogs, but only in DialogWrappers, i.e. when a separate non-settings dialog is opened with my settings inside them. I should considering opening an issue at JetBrains' issue tracker asking them to implement this feature, though it may have been a deliberate design decision.