Bug 1094031 - Let LayoutManager._updateCurrentPage() use LayoutNormalizer._normalizeKey()

- Extract a new class LayoutKeyNormalizer from LayoutNormalizer, which can be used by LayoutNormalizer and LayoutManager.
Bug 1098162 - [stingray][smart-system] Add spatial navigation to context menu
Merge pull request #26274 from mnjul/bug_1094031_use_normalier_in_layout_manager

Bug 1094031 - Let LayoutManager._updateCurrentPage() use LayoutNormalizer._normalizeKey(). r=timdream
Merge pull request #26105 from rexboy7/1098162-contextmenu-smart-system

Bug 1098162 - [stingray][smart-system] Add spatial navigation to context...　r=johnhu,dwi2
WIP Bug 1094094