plugin dependencies in metadata

add inter-plugin dependencies to package metadata

example: uuid function plugin needs uuid datatype plugin. If hypothetically the latter would've been in a separate package, the former would need to tell that to the package manager.

It's easy:

MYSQL_ADD_PLUGIN(func_uuid

                 plugin.cc item_uuidfunc.cc common.cc

                 RECOMPILE_FOR_EMBEDDED MODULE_ONLY

                 PLUGIN_DEPENDS type_uuid)

(PLUGIN_DEPENDS not DEPENDS because the latter is for cmake build-link-time dependencies).

For this to work, server package has to provide MariaDB-plugin-type_uud.