Issue #3470239: Add .gitlab-ci.yml and adjust composer.json to conform with the drupal standard

.gitlab-ci.yml

+# GitLabCI template for Drupal projects.
+#
+# This template is designed to give any Contrib maintainer everything they need to test, without requiring modification.
+# It is also designed to keep up to date with Core Development automatically through the use of include files that can be centrally maintained.
+# As long as you include the project, ref and three files below, any future updates added by the Drupal Association will be used in your
+# pipelines automatically. However, you can modify this template if you have additional needs for your project.
+# The full documentation is on https://project.pages.drupalcode.org/gitlab_templates/
+################
+
+# For information on alternative values for 'ref' see https://project.pages.drupalcode.org/gitlab_templates/info/templates-version/
+# To test a Drupal 7 project, change the first include filename from .main.yml to .main-d7.yml
+include:
+  - project: $_GITLAB_TEMPLATES_REPO
+    ref: $_GITLAB_TEMPLATES_REF
+    file:
+      - "/includes/include.drupalci.main.yml"
+      - "/includes/include.drupalci.variables.yml"
+      - "/includes/include.drupalci.workflows.yml"
+
+################
+# Pipeline configuration variables are defined with default values and descriptions in the file
+# https://git.drupalcode.org/project/gitlab_templates/-/blob/main/includes/include.drupalci.variables.yml
+# Uncomment the lines below if you want to override any of the variables. The following is just an example.
+################
+variables:
+  OPT_IN_TEST_PREVIOUS_MINOR: '1'
+  OPT_IN_TEST_NEXT_MAJOR: '1'

composer.json

 {
     "name": "drupal/extra_field",
+    "description": "Provides a plugin type for extra fields that look like real fields, but do not store data.",
     "type": "drupal-module",
+    "homepage": "https://www.drupal.org/project/extra_field",
+    "license": "GPL-2.0+",
+    "minimum-stability": "dev",
+    "support": {
+        "issues": "https://www.drupal.org/project/issues/extra_field",
+        "source": "https://www.drupal.org/project/extra_field"
+    },
     "extra": {
         "drush": {
             "services": {