Fix Ozone keyboard layout to handle German Neo 2.

1. Adds a DOM UI Events |key| for XKB's 'Shift Level 5'.
2. Sets EF_MOD3_DOWN while CapsLock is down regardless of its mapping,
to match X11 handling of ChromeOS-patched XKB configuration.

BUG=495277

Review URL: https://codereview.chromium.org/1165223003

Cr-Commit-Position: refs/heads/master@{#333948}
4 files changed