Refactor RichFormatting extension and HTML deserialization

What's Changed

• Reorganize extension ID constants by @e1himself in #205
• Refactor - Split RichFormatting extension by @e1himself in #206
• [MT-5018] Refactor - HTML deserialization by @e1himself in #208
• [MT-5018] Refactor - Html deserialization configuration & composition by @e1himself in #209
• [MT-5018] Refactor - Extract Slate content pasting logic into an extension by @e1himself in #210
• [MT-5018] Refactor - Simplify html parsing code by @e1himself in #212

Full Changelog: v0.40.8...v0.41.0