Add initial search to savedata manager

[unknownbrackets]

This adds a button to type a term, and does a simple search for that term among the list.

Some improvements that would still be good, but don't block usefulness:

• Better lowercasing for search (Unicode aware), maybe even romanji match for the common case of Japanese names.
• Inline search field entry on desktop / separate keyboard devices, and filter as you type.
• Some sort of throbber as it searches (currently async, but no indication of progress.)
• Maybe clearer indication to clear your search (considered swapping "Search" to "Clear Search"...)

Thought this might be an obvious application of #14202, but of course the delayed loading of ginfo made it more complex. That's actually a problem if we expose to accessibility anyway, since Draw is not really relevant...

Still, I think this is a very useful place for UI search. Other candidates:

• Recent list (not sure where to put it...)
• Other game lists, including remote browsing.
• System info (namely extensions lists.)

-[Unknown]

[hrydgard]

Finally got around to try this. The Search button is a little too off in the corner, not sure where to best put it though. Code looks good, merging.

[unknownbrackets]

I suppose I could do what all the cool kids do and hide it and the sorting options in a tiny button with three dots inside it.

Though I'm being slightly sarcastic, it might in fact be easier to notice for people that way.

-[Unknown]