Add MindsDB SQL Support for CREATE, UPDATE, and DROP Skill

[tmichaeldb]

As part of our LLM Agents design we need SQL support for creating, updating, and dropping skills.

Example Usage

Create

CREATE SKILL my_skill
USING
type = 'knowledge_base',
source = 'my_kb'

Update

UPDATE SKILL my_skill
SET
source = 'new_source'

Drop

DROP SKILL my_skill

[dusvyat]

nice one, lgtm