[INTERNAL][FIX] sap.m.TileContainer: Keyboard handling

Implemented the new points in the specification:
-Changed the focused element when the tile container receives focus with SHIFT+TAB: Now tile's last focusable descendant receives the focus, not the tile itself.
-CTRL+HOME, CTRL+END, CTRL+UP, CTRL+DOWN, CTRL+LEFT, CTRL+RIGHT, DELETE implemented.

Change-Id: I19a3b0725d8d1c6a1904b4dd234c1a2d4a1b4839
Merge "[INTERNAL][FIX] sap.m.TileContainer: Keyboard handling"