Bug 2022529 - Add longfox secret setting, game state and unit tests r=titooan

[I had to rebase this PR](mozilla-firefox/firefox#119) to pick up some secret settings changes.

This PR adds the switch and the game state and unit tests

[try is running here](https://treeherder.mozilla.org/jobs?repo=try&landoCommitID=186523)

Pull request: mozilla-firefox/firefox#134

UltraBlame original commit: 3ffd4787eede9c3f623e5a1f07c0eb8b55788f53

Author: marco-c

mobile/android/fenix/app/longfox/src/main/kotlin/org/mozilla/fenix/longfox/Direction.kt

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+/
+*
+*
+This
+Source
+Code
+Form
+is
+subject
+to
+the
+terms
+of
+the
+Mozilla
+Public
+*
+License
+v
+.
+2
+.
+0
+.
+If
+a
+copy
+of
+the
+MPL
+was
+not
+distributed
+with
+this
+*
+file
+You
+can
+obtain
+one
+at
+http
+:
+/
+/
+mozilla
+.
+org
+/
+MPL
+/
+2
+.
+0
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+.
+*
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+.
+mozilla
+.
+fenix
+.
+longfox
+/
+*
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+describes
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+concept
+of
+which
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+body
+part
+is
+pointing
+.
+*
+/
+enum
+class
+Direction
+{
+UP
+DOWN
+LEFT
+RIGHT
+}