fix(v2): fix contentTitle issues when markdown h1 title contains code blocks (#4882)

* attempt to fix contentTitle issues when markdown h1 title contains inline code blocks

* mention hide_title frontmatter only prevents frontmatter.title from being added in the dom (not a markdown # title in content)

* alwayss insert MainHeading under the div.markdown container for consistency

* ensure MainHeading has no useless id

* revert https://github.com/facebook/docusaurus/pull/4859 as it's now useless: docMeta.title contains the text/frontmatter title in priority over the contentTitle

* fix docs test after revert

* improve markdownParser and fix tests

* fix docs tests

* markdownParser: restore option to remove contentTitle (mostly for blog plugin)

* use removeContentTitle for blog

packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/index.test.ts.snap

@@ -168,7 +168,7 @@ Object {
   \\"unversionedId\\": \\"foo/bar\\",
   \\"id\\": \\"foo/bar\\",
   \\"isDocsHomePage\\": false,
-  \\"title\\": \\"Remarkable\\",
+  \\"title\\": \\"Bar\\",
   \\"description\\": \\"This is custom description\\",
   \\"source\\": \\"@site/docs/foo/bar.md\\",
   \\"sourceDirName\\": \\"foo\\",
@@ -190,7 +190,7 @@ Object {
   \\"unversionedId\\": \\"foo/baz\\",
   \\"id\\": \\"foo/baz\\",
   \\"isDocsHomePage\\": false,
-  \\"title\\": \\"Baz markdown title\\",
+  \\"title\\": \\"baz\\",
   \\"description\\": \\"Images\\",
   \\"source\\": \\"@site/docs/foo/baz.md\\",
   \\"sourceDirName\\": \\"foo\\",
@@ -418,12 +418,12 @@ Object {
             \\"items\\": [
               {
                 \\"type\\": \\"link\\",
-                \\"label\\": \\"Remarkable\\",
+                \\"label\\": \\"Bar\\",
                 \\"href\\": \\"/docs/foo/bar\\"
               },
               {
                 \\"type\\": \\"link\\",
-                \\"label\\": \\"Baz markdown title\\",
+                \\"label\\": \\"baz\\",
                 \\"href\\": \\"/docs/foo/bazSlug.html\\"
               }
             ]

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

@@ -180,7 +180,7 @@ describe('simple site', () => {
       isDocsHomePage: false,
       permalink: '/docs/foo/bar',
       slug: '/foo/bar',
-      title: 'Remarkable',
+      title: 'Bar',
       description: 'This is custom description',
       frontMatter: {
         description: 'This is custom description',
@@ -254,7 +254,7 @@ describe('simple site', () => {
       isDocsHomePage: true,
       permalink: '/docs/',
       slug: '/',
-      title: 'Remarkable',
+      title: 'Bar',
       description: 'This is custom description',
       frontMatter: {
         description: 'This is custom description',
@@ -286,7 +286,7 @@ describe('simple site', () => {
       isDocsHomePage: false,
       permalink: '/docs/foo/bazSlug.html',
       slug: '/foo/bazSlug.html',
-      title: 'Baz markdown title',
+      title: 'baz',
       editUrl:
         'https://github.com/facebook/docusaurus/edit/master/website/docs/foo/baz.md',
       description: 'Images',
@@ -345,7 +345,7 @@ describe('simple site', () => {
       isDocsHomePage: false,
       permalink: '/docs/foo/bazSlug.html',
       slug: '/foo/bazSlug.html',
-      title: 'Baz markdown title',
+      title: 'baz',
       editUrl: hardcodedEditUrl,
       description: 'Images',
       frontMatter: {

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

@@ -375,7 +375,7 @@ describe('simple website', () => {
         'foo',
         'bar.md',
       ),
-      title: 'Remarkable',
+      title: 'Bar',
       description: 'This is custom description',
       frontMatter: {
         description: 'This is custom description',