Deb: Use --fail-missing and ensure the not-installed list is up-to-date

Make the Debian build fail if it detects that the build (CMake) created
files that are not used in any package nor accounted in the special
not-installed file.

Stop creating symbolic links in Debian packaging for files that the CMake
build already created.

Document known cases of files that are intentionally not installed.
Leave the rest in the not-installed list for visibility. The list can
later be trimmed down and having the --fail-missing will prevent any new
unaccounted files from being introduced.

Note that despite extensive refactoring in the Debian packaging files,
there was no changes in the packages produced as verified by package
files lists before and after.

debian/libmariadb-dev.install

@@ -1,3 +1,4 @@
+usr/bin/mariadb-config
 usr/bin/mariadb_config
 usr/include/mariadb/errmsg.h
 usr/include/mariadb/ma_list.h