feat: doc tags (same as blog tags) (#3646)

* [v2] tags to doc, same as tags to blog - [IN PROGRESS]

- Addition of plugin-content-docs

- Addition of DocTagsListPage in `docusaurus-theme-classic`

! Error exists for this commit towards the theme aspect and help required.

Commit towards #3434

* docs: make tags list page work

* temp: disable onBrokenLinks

* theme bootstrap: create DocTagsListPage

* DocTagsPage added and functionality too

- individual doc tag page added to show docs for that specific tag

* Added all Docs Tags Link

* add some shared tag utils

* move tag tests to _dogfooding

* fix type

* fix some tests

* fix blog test

* refactor blog post tags handling

* better yaml tag examples

* better dogfood md files

* refactor and factorize theme tag components

* finish DocTagDocListPage

* Extract DocItemFooter + add inline tag list

* minor fix

* better typings

* fix versions.test.ts tests

* add tests for doc tags

* fix tests

* test toTagDocListProp

* move shared theme code to tagUtils

* Add new theme translation keys

* move common theme code to tagUtils + add tests

* update-code-translations should handle theme-common

* update french translation

* revert add translation

* fix pluralization problem in theme.docs.tagDocListPageTitle

* add theme component configuration options

* add more tags tests

* add documentation for docs tagging

Co-authored-by: slorber <lorber.sebastien@gmail.com>

packages/docusaurus-plugin-content-docs/src/__tests__/props.test.ts

@@ -0,0 +1,62 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {toTagDocListProp} from '../props';
+
+describe('toTagDocListProp', () => {
+  type Params = Parameters<typeof toTagDocListProp>[0];
+  type Tag = Params['tag'];
+  type Doc = Params['docs'][number];
+
+  const allTagsPath = '/all/tags';
+
+  test('should work', () => {
+    const tag: Tag = {
+      name: 'tag1',
+      permalink: '/tag1',
+      docIds: ['id1', 'id3'],
+    };
+
+    const doc1: Doc = {
+      id: 'id1',
+      title: 'ZZZ 1',
+      description: 'Description 1',
+      permalink: '/doc1',
+    };
+    const doc2: Doc = {
+      id: 'id2',
+      title: 'XXX 2',
+      description: 'Description 2',
+      permalink: '/doc2',
+    };
+    const doc3: Doc = {
+      id: 'id3',
+      title: 'AAA 3',
+      description: 'Description 3',
+      permalink: '/doc3',
+    };
+    const doc4: Doc = {
+      id: 'id4',
+      title: 'UUU 4',
+      description: 'Description 4',
+      permalink: '/doc4',
+    };
+
+    const result = toTagDocListProp({
+      allTagsPath,
+      tag,
+      docs: [doc1, doc2, doc3, doc4],
+    });
+
+    expect(result).toEqual({
+      allTagsPath,
+      name: tag.name,
+      permalink: tag.permalink,
+      docs: [doc3, doc1], // docs sorted by title, ignore "id5" absence
+    });
+  });
+});