feat: support keywords 'check' and 'checks'

[tibatob]

Hi

This PR will add support for the check-constraints syntax introduced to dbml in November 2025.

Either form (inline on column or table level checks) are supported.

Table users {
  name varchar(255) [not null]
  age integer [check: `age >= 0`]

  checks {
    `char_length(name) > 3` [name: 'chk_name_min_lenght']
  }

[linux-china]

any news to merge?