Added submitSymfonyForm function

[TavoNiievez]

While testing forms in Symfony it is very common to have to repeat the form name in different places in the method to comply with the Symfony naming format:

	$I->submitForm('form[name={form_name}]', [
		'{form_name}[{field_key}]' => '{field_value}',
		'{form_name}[{field_key}]' => '{field_value}'
	], '{form_name}_submit');

However this ruins the readability of the test and makes the code much more verbose:

	$I->submitForm('form[name=user_update_password_form]', [
		'user_update_password_form[oldPassword]'      => '123456',
		'user_update_password_form[password][first]'  => '654321',
		'user_update_password_form[password][second]' => '654321'
	], 'user_update_password_form_submit');

That is why i write this function that allows you to take advantage of the fact that the naming format is always the same, and allows you to simplify the action of submitting a form:

	$I->submitSymfonyForm('user_update_password_form', [
		'[oldPassword]'      => '123456',
		'[password][first]'  => '654321',
		'[password][second]' => '654321'
	]);

For the few who do edit this format in their applications and create something super-custom there is always the option to use the base ->submitForm() function, so this is basically a shortcut alias function.

The improvement in readability is significant.

[DavertMik]

from this description it is not clear when should I use submitSimfonyForm and submitForm
so a small description why you would need to use this method over submitForm is required