MDEV-21303 Make executables MariaDB named

To change all executables to have a mariadb name I had to:
- Do name changes in every CMakeLists.txt that produces executables
- CREATE_MARIADB_SYMLINK was removed and GET_SYMLINK added by Wlad to reuse the function in other places also
- The scripts/CMakeLists.txt could make use of GET_SYMLINK instead of introducing redundant code, but I thought I'll leave that for next release
- A lot of changes to debian/.install and debian/.links files due to swapping of real executable and symlink. I did not however change the name of the manpages, so the real name is still mysql there and mariadb are symlinks.
- The Windows part needed a change now when we made the executables mariadb -named. MSI (and ZIP) do not support symlinks and to not break backward compatibility we had to include mysql named binaries also. Done by Wlad

debian/libmariadb-dev.install

@@ -1,4 +1,4 @@
-usr/bin/mariadb_config
+usr/bin/mariadb-config
 usr/include/mariadb
 usr/lib/*/libmariadb.so
 usr/lib/*/libmariadbclient.a
@@ -7,3 +7,4 @@ usr/lib/*/libmysqlservices.a
 usr/lib/*/pkgconfig/mariadb.pc
 usr/share/aclocal/mysql.m4
 usr/share/man/man1/mysql_config.1
+usr/share/man/man1/mariadb-config.1