Use RichTextDisplay in posting details page

[Boyazhang1]

Ticket link

Closes #131

Implementation description

• Wrapped the postingDetails description inside the RichTextDisplay component created in Display rich text in Admin "Review and Post" #130

Steps to test

1. Follow testing instructions in Add Posting Details Page UI and Query #140 , but replace the description field of the createPosting mutation with the following richText samples:

• "{"blocks":[{"key":"2ggjh","text":"hi","type":"ordered-list-item","depth":0,"inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"2nlb2","text":"aewf","type":"ordered-list-item","depth":0,"inlineStyleRanges":[{"offset":0,"length":4,"style":"BOLD"}],"entityRanges":[],"data":{}},{"key":"6a81d","text":"asf","type":"ordered-list-item","depth":0,"inlineStyleRanges":[{"offset":0,"length":3,"style":"BOLD"},{"offset":0,"length":3,"style":"UNDERLINE"}],"entityRanges":[],"data":{}}],"entityMap":{}}"
• "{"blocks":[{"key":"2ggjh","text":"ajwefiojeio","type":"unordered-list-item","depth":0,"inlineStyleRanges":[],"entityRanges":[],"data":{}},{"key":"80c8b","text":"jasidf","type":"unordered-list-item","depth":0,"inlineStyleRanges":[{"offset":0,"length":6,"style":"BOLD"},{"offset":0,"length":6,"style":"UNDERLINE"},{"offset":0,"length":6,"style":"ITALIC"}],"entityRanges":[],"data":{}},{"key":"4qepd","text":"ajewoifjwejo","type":"unstyled","depth":0,"inlineStyleRanges":[{"offset":0,"length":12,"style":"BOLD"},{"offset":0,"length":12,"style":"UNDERLINE"},{"offset":0,"length":12,"style":"ITALIC"}],"entityRanges":[],"data":{}}],"entityMap":{}}"

Which should display the following

What should reviewers focus on?

• Verify the description is displayed properly in richtext

Checklist

• [x ] My PR name is descriptive and in imperative tense
• [ x] My commit messages are descriptive and in imperative tense. My commits are atomic and trivial commits are squashed or fixup'd into non-trivial commits
• [x ] I have run the appropriate linter(s)
• [x ] I have requested a review from the PL, as well as other devs who have background knowledge on this PR or who will be building on top of this PR

[github-actions]

Visit the preview URL for this PR (updated for commit ae0fca2):

https://sistering-dev--pr239-boya-display-richtex-xmtuxqs3.web.app

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[sherryhli]

LGTM!