[Rich text editor] Integrate rich text editor library (#1172)

* Integrate rich text editor

* Also increase swapfile size in test CI

Fixes issue where screenshot tests are terminated due to lack of CI
resources.

See https://github.com/actions/runner-images/discussions/7188#discussioncomment-6750749

---------

Co-authored-by: ElementBot <benoitm+elementbot@element.io>

.github/workflows/tests.yml

@@ -22,6 +22,16 @@ jobs:
       group: ${{ github.ref == 'refs/heads/main' && format('unit-tests-main-{0}', github.sha) || github.ref == 'refs/heads/develop' && format('unit-tests-develop-{0}', github.sha) || format('unit-tests-{0}', github.ref) }}
       cancel-in-progress: true
     steps:
+      # Increase swapfile size to prevent screenshot tests getting terminated
+      # https://github.com/actions/runner-images/discussions/7188#discussioncomment-6750749
+      - name: 💽 Increase swapfile size
+        run: |
+          sudo swapoff -a
+          sudo fallocate -l 8G /mnt/swapfile
+          sudo chmod 600 /mnt/swapfile
+          sudo mkswap /mnt/swapfile
+          sudo swapon /mnt/swapfile
+          sudo swapon --show
       - name: ⏬ Checkout with LFS
         uses: nschloe/action-cached-lfs-checkout@v1.2.2
         with: