Handle special key events for TV remote controls

[swift-kim]

A temporary fix for flutter-tizen/flutter-tizen#319. May also fix #229.

I don't have an access to TV devices right now. Could anybody test this change on a real TV device?

Things to test:

• Pressing the Play/Pause button (on smart remote control) doesn't trigger the "Not Available" popup.
• Pressing the Channel List button (on classic remote control) doesn't crash the app.
• Pressing the Menu button (on classic remote control) doesn't generate an exception.

How to test (details):

$ TIZEN_ENGINE_GITHUB_RUN_ID=1718348087 flutter-tizen precache --tizen
$ flutter-tizen run --verbose-system-logs

[xiaowei-guan]

when I don't apply this patch, I can't reproduce Play/Pause button issue on TV device.

• Pressing the Play/Pause button (on smart remote control) doesn't trigger the "Not Available" popup.
• Pressing the Channel List button (on classic remote control) doesn't crash the app.
• Pressing the Menu button (on classic remote control) doesn't generate an exception.

when I apply this patch on TV device, no channel list and play/pause issue, but still has menu button issue:

• Pressing the Play/Pause button (on smart remote control) doesn't trigger the "Not Available" popup.
• Pressing the Channel List button (on classic remote control) doesn't crash the app.
• Pressing the Menu button (on classic remote control) doesn't generate an exception.

[swift-kim]

@xiaowei-guan Thanks for the check. I'll check again and provide a better solution after the holidays :)

[swift-kim]

Closing in favor of #234.

@xiaowei-guan You can test the new PR if you want to check if #229 has been resolved.