minor #8262 Move group_service_resolver.rst to form folder (afurculita, javiereguiluz)

This PR was submitted for the master branch but it was merged into the 2.7 branch instead (closes #8262).

Discussion
----------

Move group_service_resolver.rst to form folder

The `validation\group_service_resolver.rst` file is related more the Form component than to the Validator component. This can't be part of the documentation for the Validator component because it is about an implementation detail from the Form component.

Commits
-------

55bce77 Added a missing redirection
b5d113d Update validation_group_service_resolver.rst
a089159 Update redirection_map
c4fc122 Update button_based_validation.rst
b33a9ac Delete group_service_resolver.rst
0559274 Create validation_group_service_resolver.rst

Author: xabbuh

_build/redirection_map

@@ -255,7 +255,7 @@
 /cookbook/upgrade/minor_version /setup/upgrade_major
 /cookbook/upgrade/patch_version /upgrade/bundles
 /cookbook/validation/custom_constraint /validation/custom_constraint
-/cookbook/validation/group_service_resolver /validation/group_service_resolver
+/cookbook/validation/group_service_resolver /form/validation_group_service_resolver
 /cookbook/validation/index /validation
 /cookbook/validation/severity /validation/severity
 /cookbook/web_server/built_in /setup/built_in_web_server
@@ -326,3 +326,4 @@
 /install/bundles /setup/bundles
 /form /forms
 /testing/simulating_authentication /testing/http_authentication
+/validation/group_service_resolver /form/validation_group_service_resolver

form/button_based_validation.rst

@@ -39,4 +39,4 @@ large or whether you tried to submit text in a number field.
 .. seealso::
 
     To see how to use a service to resolve ``validation_groups`` dynamically
-    read the :doc:`/validation/group_service_resolver` article.
+    read the :doc:`/form/validation_group_service_resolver` article.

validation/group_service_resolver.rst renamed to form/validation_group_service_resolver.rst

@@ -1,5 +1,5 @@
-How to Dynamically Configure Validation Groups
-==============================================
+How to Dynamically Configure Form Validation Groups
+===================================================
 
 Sometimes you need advanced logic to determine the validation groups. If they
 can't be determined by a simple callback, you can use a service. Create a
@@ -47,7 +47,7 @@ Then in your form, inject the resolver and set it as the ``validation_groups``.
     namespace AppBundle\Form;
 
     use AppBundle\Validator\ValidationGroupResolver;
-    use Symfony\Component\Form\AbstractType;
+    use Symfony\Component\Form\AbstractType
     use Symfony\Component\OptionsResolver\OptionsResolver;
 
     class MyClassType extends AbstractType