Add no-hardcoded-urls rule

Related to gitlab-org/gitlab#560240 and gitlab-org/gitlab#579401

Background

We haven't had strict guidelines around constructing URLs in GitLab and as a result we have a number of instances where we construct URLs on the frontend. This can cause issues with the relative_url_root setting, Geo, and in the future organization scoped routes. In gitlab-org/gitlab!215122 (merged) I added some developer documentation that now lives at https://docs.gitlab.com/development/urls_in_gitlab/. This MR goes one more step and introduces a ESLint rule that prevents hardcoding or constructing URLs on the frontend. This should help us prep for organization scoped routes and reduce relative_url_root setting and Geo bugs.

Screenshots

How to test

1. Install yalc - https://github.com/wclr/yalc
2. Pull down this MR
3. Run yalc publish
4. In gitlab-org/gitlab project run yalc add @gitlab/eslint-plugin
5. Apply this patch (pbpaste | git apply)

diff --git a/eslint.config.mjs b/eslint.config.mjs
index 7015081371df..b4d788535908 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -252,6 +252,41 @@ export default [
       '@gitlab/vue-tailwind-no-interpolation': 'error',
       '@gitlab/tailwind-no-max-width-media-queries': 'error',
       '@gitlab/vue-tailwind-no-max-width-media-queries': 'error',
+      '@gitlab/no-hardcoded-urls': [
+        'error',
+        {
+          allowedKeys: ['path', 'redirect'],
+          allowedFunctions: ['helpPagePath'],
+          allowedInterpolationVariables: [
+            'FORUM_URL',
+            'DOCS_URL',
+            'PROMO_URL',
+            'CONTRIBUTE_URL',
+            'DOCS_URL_IN_EE_DIR',
+            'CUSTOMERS_PORTAL_URL',
+          ],
+          allowedPatterns: ['\\/api\\/:version'],
+          disallowedObjectProperties: ['relative_url_root'],
+        },
+      ],
+      '@gitlab/vue-no-hardcoded-urls': [
+        'error',
+        {
+          allowedVueComponents: ['help-page-link'],
+          allowedKeys: ['path', 'redirect'],
+          allowedFunctions: ['helpPagePath'],
+          allowedInterpolationVariables: [
+            'FORUM_URL',
+            'DOCS_URL',
+            'PROMO_URL',
+            'CONTRIBUTE_URL',
+            'DOCS_URL_IN_EE_DIR',
+            'CUSTOMERS_PORTAL_URL',
+          ],
+          allowedPatterns: ['\\/api\\/:version'],
+          disallowedObjectProperties: ['relative_url_root'],
+        },
+      ],
 
       'no-param-reassign': [
         'error',
@@ -491,6 +526,8 @@ export default [
       'require-await': 'error',
       'import/no-dynamic-require': 'off',
       'no-import-assign': 'off',
+      '@gitlab/no-hardcoded-urls': 'off',
+      '@gitlab/vue-no-hardcoded-urls': 'off',
 
       'no-restricted-syntax': [
         'error',
@@ -626,6 +663,8 @@ export default [
       'import/no-nodejs-modules': 'off',
       'filenames/match-regex': 'off',
       'no-console': 'off',
+      '@gitlab/no-hardcoded-urls': 'off',
+      '@gitlab/vue-no-hardcoded-urls': 'off',
     },
   },
   {
@@ -634,6 +673,8 @@ export default [
     rules: {
       'filenames/match-regex': 'off',
       '@gitlab/require-i18n-strings': 'off',
+      '@gitlab/no-hardcoded-urls': 'off',
+      '@gitlab/vue-no-hardcoded-urls': 'off',
       'import/no-unresolved': [
         'error',
         // The test fixtures are dynamically generated in CI during
@@ -725,6 +766,8 @@ export default [
       'filenames/match-regex': 'off',
       'no-console': 'off',
       'import/no-unresolved': 'off',
+      '@gitlab/no-hardcoded-urls': 'off',
+      '@gitlab/vue-no-hardcoded-urls': 'off',
     },
   },
 
@@ -785,6 +828,8 @@ export default [
     rules: {
       '@gitlab/require-i18n-strings': 'off',
       'no-restricted-imports': 'off',
+      '@gitlab/no-hardcoded-urls': 'off',
+      '@gitlab/vue-no-hardcoded-urls': 'off',
     },
   },
 
@@ -818,6 +863,15 @@ export default [
       'func-names': 'off',
       // k6 globals are defined above
       'no-undef': 'off',
+      '@gitlab/no-hardcoded-urls': 'off',
+      '@gitlab/vue-no-hardcoded-urls': 'off',
+    },
+  },
+  {
+    files: ['app/assets/javascripts/**/mock_data.js'],
+    rules: {
+      '@gitlab/no-hardcoded-urls': 'off',
+      '@gitlab/vue-no-hardcoded-urls': 'off',
     },
   },
   ...jhConfigs,

1. Run ./scripts/dump_graphql_schema. You may have to download job artifacts from the latest generate-apollo-graphql-schema job and manually add the gitlab_schema_apollo.graphql file to tmp/tests/graphql
2. Run yarn lint:eslint --no-cache

Next steps after this is merged

1. Update eslint.config.mjs with above patch
2. Run node scripts/frontend/generate_eslint_todo_list.mjs @gitlab/no-hardcoded-urls and node scripts/frontend/generate_eslint_todo_list.mjs @gitlab/vue-no-hardcoded-urls to generate todo lists for fixing these rules.
3. Group files by GitLab team first using the .gitlab/CODEOWNERS and then manually. Create an issue for each team with list of files that need to be fixed.
4. Work with teams to fix the violations.