move config/ to data/config/

Summary:
this is part of the datadir distribution, it should not be in a different
directory than the rest of the datadir distribution

the gnu coding standards (https://www.gnu.org/prep/standards/html_node/Directory-Variables.html)
define 'datadir' as:

The directory for installing idiosyncratic read-only architecture-independent
data files for this program. This is usually the same place as ‘datarootdir’,
but we use the two separate variables so that you can move these program-specific
files without altering the location for Info files, man pages, etc.

This should normally be /usr/local/share, but write it as $(datarootdir).
(If you are using Autoconf, write it as ‘@datadir@’.)

The definition of ‘datadir’ is the same for all packages, so you should install your
data in a subdirectory thereof. Most packages install their data under $(datadir)/package-name/.

while this text has no clear requirement or suggestion for a corresponding
repository layout, projects typically employ a certain consistency in their
repository layout both for ease of maintenance and ease of learning for new
contributors.

this project has both a data/ directory, which contains the datadir distribution,
as well as the config/ directory, which also contains the datadir distribution.
this complicates matters both for active maintainers/developers who must
remember that the repository and build tree layouts have this exception,
and for new contributors who will initially be confused by this exception

other well-organized open source projects, such as wayland, have chosen to not
use a data/ directory. these projects have the datadir distribution in the base
directory of the repositor, which is a fine practice as it maintains consistency
for the project since all the files for the datadir distribution are in the same
directory.

by applying this patch, the project will move towards a more easily readable and
learnable layout. current and future developers will no longer need to wonder why
this directory is outside of the data/ directory, and anyone attempting to reference
these files from the source/build trees will be able to do so more easily

ref D6013

Reviewers: cedric, raster, bu5hm4n

Reviewed By: raster

Subscribers: devilhorns

Tags: #enlightenment-git

Differential Revision: https://phab.enlightenment.org/D6154

meson.build

@@ -346,9 +346,9 @@ subdir('src/bin')
 
 subdir('src/modules')
 
-subdir('config')
 
 subdir('data/backgrounds')
+subdir('data/config')
 subdir('data/desktop')
 subdir('data/etc')
 subdir('data/favorites')