Move the remaining 60 or so test files into an entry/ subdirectory.
These cover general entry types and features: entry args, fill, text,
env, compress, replace, template, collection, ELF, overlap, listing,
sections, symlink, TEE OS, and other miscellaneous entries. Drop the
numeric prefixes and update all references.

Signed-off-by: Simon Glass <simon.glass@canonical.com>
Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>

Collections can used to collect the contents of other entries into a
single entry, but they result in a single entry, with the original entries
'left behind' in their old place.

It is useful to be able to specific a set of entries ones and have it used
in multiple images, or parts of an image.

Implement this mechanism.

Signed-off-by: Simon Glass <sjg@chromium.org>