Remove global h2 css rule in favour of heading styles/components (#32969)

* Remove global h2 css rule in favour of heading styles/components

* Use Compound Heading in shared-components

and forbid hX elements

* Use Compound Heading in settings

add back margin to some legacy headings

* Tweak some headings

* Update screenshots

* Update screenshots

* Update snapshots

* Tweak .gitignore

* Update snapshots

* Iterate

* Update screenshots

* Update screenshots

* Update screenshot

apps/web/test/unit-tests/components/structures/__snapshots__/MessagePanel-test.tsx.snap

@@ -47,11 +47,12 @@ exports[`MessagePanel should handle lots of membership events quickly 1`] = `
               role="none"
             />
             <div
-              class="_flex_4dswl_9 _content_5dcky_8"
+              class="_flex_4dswl_9 _content_u6fft_8"
               style="--mx-flex-display: flex; --mx-flex-direction: row; --mx-flex-align: start; --mx-flex-justify: start; --mx-flex-gap: 0; --mx-flex-wrap: nowrap;"
             >
               <h2
                 aria-hidden="true"
+                class="_typography_6v6n8_153 _font-heading-lg-regular_6v6n8_121"
               >
                 Thu, Jan 1, 1970
               </h2>

apps/web/test/unit-tests/components/views/dialogs/__snapshots__/MessageEditHistoryDialog-test.tsx.snap

@@ -49,11 +49,12 @@ exports[`<MessageEditHistory /> should match the snapshot 1`] = `
                   role="none"
                 />
                 <div
-                  class="_flex_4dswl_9 _content_5dcky_8"
+                  class="_flex_4dswl_9 _content_u6fft_8"
                   style="--mx-flex-display: flex; --mx-flex-direction: row; --mx-flex-align: start; --mx-flex-justify: start; --mx-flex-gap: 0; --mx-flex-wrap: nowrap;"
                 >
                   <h2
                     aria-hidden="true"
+                    class="_typography_6v6n8_153 _font-heading-lg-regular_6v6n8_121"
                   >
                     Thu, Jan 1, 1970
                   </h2>
@@ -188,11 +189,12 @@ exports[`<MessageEditHistory /> should support events with 1`] = `
                   role="none"
                 />
                 <div
-                  class="_flex_4dswl_9 _content_5dcky_8"
+                  class="_flex_4dswl_9 _content_u6fft_8"
                   style="--mx-flex-display: flex; --mx-flex-direction: row; --mx-flex-align: start; --mx-flex-justify: start; --mx-flex-gap: 0; --mx-flex-wrap: nowrap;"
                 >
                   <h2
                     aria-hidden="true"
+                    class="_typography_6v6n8_153 _font-heading-lg-regular_6v6n8_121"
                   >
                     Thu, Jan 1, 1970
                   </h2>