IPython KaTeX rendering of comparison operators for markdown

What does this MR do?

When rendering IPython notebook markdown cells the formulas are passed to Katex. Before that the raw string is passed to marked.js to handle HTML forbidden characters. Two of these characters are the less-than-operator < and the greater-than-operator >. These characters are often used in math formulas and the replacements < and > are not well received by Katex.

Fixes: #327450 (closed)

Screenshots (strongly suggested)

Screenshot of KaTeX formulas containing < and > rendering correctly

Does this MR meet the acceptance criteria?

Conformity

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Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
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