[REQ][MySQL] Openapi data format uuid to VARCHAR UNIQUE

Is your feature request related to a problem? Please describe.

There is special Openapi data format uuid. Right now this format mapped to TEXT column type and it's not possible to add UNIQUE index to this column because of error:

#1170 - BLOB/TEXT column 'uuid' used in key specification without a key length

First of all let's check how usually uuid looks like, in PHP:

echo uniqid();
// 5d437d6a28bca

or in MySQL:

SELECT UUID();
// e6380056-b4b8-11e9-8c6e-a3c6f372608a

So, it's alphanumeric string and not too long.

Describe the solution you'd like

VARCHAR column type with limited length looks like a good fit. My suggestion is:

--- `uuid` TEXT DEFAULT NULL,
+++ `uuid` VARCHAR(255) DEFAULT NULL UNIQUE,

Additional context

I'll do this enhancement myself, just want to open discussion and track progress.

No files, tests, or entry points are named. Start by locating the MySQL schema-generation mapping for the OpenAPI uuid format and its existing tests, then verify that the generated column supports a UNIQUE index without the reported key-length error.