The Eclipse SDK is currently not being installed in the SDK image. Add it
back, remove redundant old entries in the Debos configuration and tweak
the desktop file to take into account it's new name and icon.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>

The basesdk overlay was not actually included since `debos` was not
following the symlink to the sdk one.

Avoid the symlink by getting rid for the sdk recipe of the `$arch-$type`
mechanism, which is an ancient relic inherited from the conversion from
the old `cb_build` pipeline.

Splitting the overlay into semantic units also allow us to avoid the
Eclipse icon on the base SDK desktop, where Eclipse is not installed.

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>

Copying overlay and scripts from original repository
with adaptation for Debos.

Signed-off-by: Denis Pynkin <denis.pynkin@collabora.com>
Differential Revision: https://phabricator.apertis.org/D7201