RM-287: Add Text Display

[biast12]

RM-287

Description

Adds storage for Discord Text Display form fields (component type 10).

• New nullable form_input.content column (VARCHAR(4000)), read and written by every form input query. GalleryFormInputSnapshot also gets Content.
• Create/CreateTx take a new content parameter after placeholder.
• New FormInputOptionTable.DeleteByFormInputTx deletes all options of a field inside a transaction.

Migration:

ALTER TABLE form_input ADD COLUMN IF NOT EXISTS "content" VARCHAR(4000) DEFAULT NULL;

For:
TicketsBot-cloud/worker#154
TicketsBot-cloud/dashboard#152

Type of Change

• Bug fix
• New feature
• Breaking change

Checklist

• My code follows the style of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works