fix: Annotaterb model annotation incomplete migration (#13132)

This pull request fixes the model annotation tooling due to previous
incomplete migration from `annotate` to `annotaterb` gem (#12600). It
also improves the handling of serialized values in the
`InstallationConfig` model by ensuring a default value is set,
simplifying the code, and removing a workaround for YAML
deserialization.

**Annotation tooling updates:**

* Added `.annotaterb.yml` to configure the `annotate_rb` gem with
project-specific options, centralizing annotation settings.
* Replaced the custom `auto_annotate_models.rake` task with the standard
rake task from `annotate_rb`, and added `lib/tasks/annotate_rb.rake` to
load annotation tasks in development environments.
[[1]](diffhunk://#diff-9450d2359e45f1db407b3871dde787a25d60bb721aed179a65ffd2692e95fb4bL1-L61)
[[2]](diffhunk://#diff-578cdfc7ad56637e42472ea891ea286dff8803d9a1750afdbfeafec164d9b8b2R1-R8)

**Model serialization improvements:**

* Updated the `InstallationConfig` model to set a default value for the
`serialized_value` attribute, ensuring it always has a hash with
indifferent access and removing the need for a deserialization
workaround in the `value` method.
[[1]](diffhunk://#diff-b4bdde42c1ad0f584073818bd43dbd865b1b3b50d4701b131979f900d7c68297L22-R22)
[[2]](diffhunk://#diff-b4bdde42c1ad0f584073818bd43dbd865b1b3b50d4701b131979f900d7c68297L36-L39)

---------

Co-authored-by: Sojan Jose <sojan@pepalo.com>

.annotaterb.yml

@@ -0,0 +1,65 @@
+---
+:position: before
+:position_in_additional_file_patterns: before
+:position_in_class: before
+:position_in_factory: before
+:position_in_fixture: before
+:position_in_routes: before
+:position_in_serializer: before
+:position_in_test: before
+:classified_sort: true
+:exclude_controllers: true
+:exclude_factories: true
+:exclude_fixtures: true
+:exclude_helpers: true
+:exclude_scaffolds: true
+:exclude_serializers: true
+:exclude_sti_subclasses: false
+:exclude_tests: true
+:force: false
+:format_markdown: false
+:format_rdoc: false
+:format_yard: false
+:frozen: false
+:grouped_polymorphic: false
+:ignore_model_sub_dir: false
+:ignore_unknown_models: false
+:include_version: false
+:show_check_constraints: false
+:show_complete_foreign_keys: false
+:show_foreign_keys: true
+:show_indexes: true
+:show_indexes_include: false
+:simple_indexes: false
+:sort: false
+:timestamp: false
+:trace: false
+:with_comment: true
+:with_column_comments: true
+:with_table_comments: true
+:position_of_column_comment: :with_name
+:active_admin: false
+:command:
+:debug: false
+:hide_default_column_types: json,jsonb,hstore
+:hide_limit_column_types: integer,bigint,boolean
+:timestamp_columns:
+- created_at
+- updated_at
+:ignore_columns:
+:ignore_routes:
+:models: true
+:routes: false
+:skip_on_db_migrate: false
+:target_action: :do_annotations
+:wrapper:
+:wrapper_close:
+:wrapper_open:
+:classes_default_to_s: []
+:additional_file_patterns: []
+:model_dir:
+- app/models
+- enterprise/app/models
+:require: []
+:root_dir:
+- ''