bitbake: hob: Error reports are done in a clearer way

bitbake: hob: Error reports are done in a clearer way

For long errors (bigger than 200 letters),
the text box is scrollable and resizable
and text is selectable.

Additionaly, all message dialogs are modal.
Otherwise, a user could still interact with hob
even in an error case, leading to potential problems.

See design details in related bugs.

Fixes [YOCTO #2960], [YOCTO #2983]

(Bitbake rev: be8bf02f2b347edf5514cafc6cb6a44f71118736)

Signed-off-by: Cristian Iorga <cristian.iorga@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>