perf: downgrade rehype-highlight and generate once blob url (cohere-ai#193)

* perf: downgrade rehype-highlight and generate once blob url

* fix: replace code blocks to iframe in conversation history

* refactor: run format

* refactor: pr feedback

Author: tomtobac

src/interfaces/coral_web/package-lock.json

@@ -57,7 +57,7 @@
     "react-popper": "^2.3.0",
     "react-scroll-to-bottom": "^4.2.0",
     "react-syntax-highlighter": "^15.5.0",
-    "rehype-highlight": "^7.0.0",
+    "rehype-highlight": "6.0.0",
     "rehype-katex": "^7.0.0",
     "rehype-raw": "^7.0.0",
     "remark": "^15.0.1",