Add support for ALTER TABLE MODIFY COMMENT

[alexey-milovidov]

Changelog category (leave one):

• New Feature

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Add support for ALTER TABLE MODIFY COMMENT. Note: something similar was added by an external contributor a long time ago, but the feature did not work at all and only confused users. This closes #36377.

[robot-ch-test-poll]

This is an automated comment for commit ce8ab5c with description of existing statuses. It's updated for the latest CI running
The full report is available here
The overall status of the commit is 🟡 pending

Check name	Description	Status
CI running	A meta-check that indicates the running CI. Normally, it's in success or pending state. The failed status indicates some problems with the PR	🟡 pending
Mergeable Check	Checks if all other necessary checks are successful	🟢 success

[alesapin]

I'm still here, will fix

[alexey-milovidov]

Wow, it's green!