Follow "namespace" layer structure on chromium branch

.bbappends (and related files) in Chromium branch are not following the layer namespace structure as introduced in GDP-689

For example:

• meta-genivi-dev/recipes-extended/chromium/chromium-wayland_%.bbappend
  to:
• meta-browser/recipes-browser/chromium/chromium-wayland_%.bbappend 

AC

• Move the bbappend files and related files to a meta-browser subdirectory inside meta-genivi-dev.
• Adjust bblayers.conf accordingly to include the new sub-layer