table: fold `clone_rename` into `clone`.

* specs/table_spec.yaml (std.table): Specify new behaviour with
optional `map` argument.
* lib/std/base.lua (clone): Implement new behaviours.
* lib/std/table.lua (clone_rename): Add deprecation warning, and
move out of the LDoc export table.
(clone): Update doc-comments.
* NEWS: Update.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>