lua: introduce function to check that passed value is uuid

We already have is_decimal function that checks allowed value
is decimal. After tarantool started to support UUID type it will
be quite often case to check that some value has UUID type as
well. This patch introduces "is_uuid" function for this purpose.

Closes #5171

Signed-off-by: Oleg Babin <olegrok@tarantool.org>
Reviewed-by: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
Reviewed-by: Leonid Vasiliev <lvasiliev@tarantool.org>

@TarantoolBot document
Title: uuid.is_uuid

is_uuid function returns "true" if specified value has uuid type
and "false" otherwise.