Handle KEYCODE_DPAD_CENTER and KEYCODE_ENTER - #138240

@gspencergoog I'm just now familiarizing myself with this area of the code, so before I continue along this path and add the associated tests, etc. Do you think this is a valid approach? Or would you recommend I start somewhere else?

That should be a good start. You might even be able to add it to the default shortcuts, since the select key would only be mapped on a system that produces it. Then if, say, we started mapping that key on iOS, then it would just work. We currently seem to map it already on Windows, so it would be nice if it worked there.

(triage): @mossmana said she would get back to this.

In my first pass I made a change that would have only taken effect for Android. However, now the defaults for Fuchsia, Windows and Linux have been updated as well.

@gspencergoog I'm not sure if adding to the defaults would eventually work for iOS. iOS and MacOs seem to have a different set of defaults. https://github.com/flutter/flutter/pull/138240/files#diff-f629b31e1aaf7209877c14f88326284538c1279b6bcf4859e3d4daebc889bef4R1276

I'm not sure what is going on, but every time I try to merge in the latest changes from master, there's a completely different unrelated to my changes test failure. I think I'm going to try opening up a fresh PR starting from the most recent base branch.