Resolve Recording Issues for Linux / OnePad users (#3293)

* git: Ignore uncaught linux build artifacts

* onepad-legacy: Return legitimate key event on `PADkeyEvent` call

Onepad-legacy was the plugin that was building and being used on my linux environment.  I'm not sure if t hat's expected and normal 'onepad' has yet to take over.

* onepad: Return legitimate key event on `PADkeyEvent` call

* recording: Remove unnecessary `PadKeyDispatch(ev)` wrapping func

* recording: Cleanup key event handling when GSFrame CoreThread is paused

* recording: Refactor recording status check to be more explicit

* recording: Define additional key bindings for capitalized varient

Despite the advice of the docstrings in these files, on linux this seems to be required for the bindings to consistently fire.

* onepad: Declare `AnalyzeKeyEvent` not static

* recording: Ensure file extension is appended to recording file on linux

* recording: Correct typo in comment

* recording: Better wording around linux keybinding handling

* Remove unneeded `extern`

pcsx2/Recording/NewRecordingFrame.cpp

@@ -1,5 +1,5 @@
 /*  PCSX2 - PS2 Emulator for PCs
- *  Copyright (C) 2002-2019  PCSX2 Dev Team
+ *  Copyright (C) 2002-2020  PCSX2 Dev Team
  *
  *  PCSX2 is free software: you can redistribute it and/or modify it under the terms
  *  of the GNU Lesser General Public License as published by the Free Software Found-
@@ -62,7 +62,13 @@ NewRecordingFrame::NewRecordingFrame(wxWindow *parent)
 
 wxString NewRecordingFrame::GetFile() const
 {
-	return m_filePicker->GetPath();
+	wxString path = m_filePicker->GetPath();
+	// wxWidget's removes the extension if it contains wildcards
+	// on wxGTK https://trac.wxwidgets.org/ticket/15285
+	if (!path.EndsWith(".p2m2")) {
+		return wxString::Format("%s.p2m2", path);
+	}
+	return path;
 }
 
 wxString NewRecordingFrame::GetAuthor() const