feat: deferred allocator pattern and configurable formatting support (#495)

* fix: remove debug print statements from dartFormatter function

* fix: add formatter config to all builders in end_to_end_test and regenerate code

- Added format config (page_width: 80, language_version: 3.6.0) to all builders
- Regenerated code with consistent formatting across all builders
- Ensures all generated files use the same formatting settings

* fix: remove unused imports in gql_build

- Remove unused config.dart import from ast_builder.dart
- Remove unused element.dart import from serializer_builder.dart (only element2.dart is used)

Author: knaeckeKami

codegen/end_to_end_test/build.yaml

@@ -6,11 +6,14 @@ targets:
         options:
           format:
             page_width: 80
-            language_version: '3.7.0'
+            language_version: '3.6.0'
       gql_build|req_builder:
         enabled: true
         options:
           schema: end_to_end_test|lib/graphql/schema.graphql
+          format:
+            page_width: 80
+            language_version: '3.6.0'
       gql_build|serializer_builder:
         enabled: true
         options:
@@ -29,6 +32,9 @@ targets:
       gql_build|schema_builder:
         enabled: true
         options:
+          format:
+            page_width: 80
+            language_version: '3.6.0'
           vars_create_factories: true
           enum_fallbacks:
             LengthUnit: METER
@@ -42,6 +48,9 @@ targets:
         enabled: true
         options:
           schema: end_to_end_test|lib/graphql/schema.graphql
+          format:
+            page_width: 80
+            language_version: '3.6.0'
           when_extensions:
             when: true
             maybeWhen: true
@@ -55,6 +64,9 @@ targets:
         enabled: true
         options:
           schema: end_to_end_test|lib/graphql/schema.graphql
+          format:
+            page_width: 80
+            language_version: '3.6.0'
           vars_create_factories: true
           type_overrides:
             Date: