toaster: fixes for customimage package not found

toaster: fixes for customimage package not found

For a custom image, if a search for a package results in no packages
found, then additional information should be presented to the user.
This is different than a 'no results' found for a search in other
contexts, for example, a search for a package in a non-customised build.
For a custom image, a package search failure can happen because the
package was not added to the custom image. This commit presents more
information to the user, suggesting why the package was not found in the
custom image.
The generic table view handling js changes to handle a new div
element no-results-special-... such that, if present, that template
section is shown rather than the default no-results-... section.

[YOCTO #9154]

Signed-off-by: Dave Lerner <dave.lerner@windriver.com>
Signed-off-by: Elliot Smith <elliot.smith@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>