feat: add better support for unique columns

[WellingtonNico]

Hello again!

I asked you how could I set a column as unique, you told me to use something like this:

index(ColumnIndex.unique, 'email', ['email']);

it didn't work because it generated this sql, which has a syntax error near INDEX(using postgres at least, but I checked in many AI models and both told me it is wrong for mysql too):

CREATE TABLE IF NOT EXISTS "users" (
    "id" SERIAL NOT NULL PRIMARY KEY,
    "name" VARCHAR(100) NOT NULL,
    "avatar" VARCHAR(250) NULL,
    "password" VARCHAR(200) NOT NULL,
    "email" VARCHAR(60) NOT NULL,
    "phone" VARCHAR(60) NULL,
    "description" TEXT NULL,
    "birthday" DATE NULL,
    "created_at" TIMESTAMP NULL,
    "updated_at" TIMESTAMP NULL,
    unique INDEX "email" ("email")
)

so I added an argument for each column type to generate unique columns with unique constraint, I tested for my migration and now it works, see the difference:
before:

await createTableNotExists('users', () {
      id();
      string('name', length: 100);
      string('avatar', length: 250, nullable: true);
      string('password', length: 200);
      string('email', length: 60);
      string('phone', length: 60, nullable: true);
      text('description', nullable: true);
      date('birthday', nullable: true);
      timeStamps();
      index(ColumnIndex.unique, 'email', ['email']);
});

after

await createTableNotExists('users', () {
      id();
      string('name', length: 100);
      string('avatar', length: 250, nullable: true);
      string('password', length: 200);
      string('email', length: 60,unique: true);
      string('phone', length: 60, nullable: true);
      text('description', nullable: true);
      date('birthday', nullable: true);
      timeStamps();
});

it now generates a query like this:

CREATE TABLE IF NOT EXISTS "users" (
    "id" SERIAL NOT NULL PRIMARY KEY,
    "name" VARCHAR(100) NOT NULL,
    "avatar" VARCHAR(250) NULL,
    "password" VARCHAR(200) NOT NULL,
    "email" VARCHAR(60) NOT NULL UNIQUE,
    "phone" VARCHAR(60) NULL,
    "description" TEXT NULL,
    "birthday" DATE NULL,
    "created_at" TIMESTAMP NULL,
    "updated_at" TIMESTAMP NULL
)

happy to help!

[WellingtonNico]

any updates here guys?

[javad-zobeidi]

@WellingtonNico What if we have a combination of two columns?

ex:
combination mobile with email

[WellingtonNico]

@WellingtonNico What if we have a combination of two columns?

ex: combination mobile with email

I think it's not a commom usage, thats way PRIMARY is made for...

[javad-zobeidi]

@WellingtonNico
Thank you for the PR