Limit wiki text width on fluid layouts

What does this MR do and why?

For users with the fluid layout preference, this MR introduces width limit of 992px for text blocks in wiki to improve readability.

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. In User preferences, select "Fluid" as the preferred layout
2. Open or create a wiki
3. on the wiki page, add a wide content element, such as a GLQL table with lots of fields or a HTML table.
4. save and view how the text blocks are limited in width while wider elements utilize the entire screen width.

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