Add math environment `quantikz` from package `quantikz`

[ArvinSKushwaha]

The environment quantikz from the package quantikz is not treated as a math environment.

Here is some test code for a possible mathzone check:

\usepackage{quantikz}

\begin{quantikz}
    q_{1} & \gate[4]{e^{i t H_C}} & \\
    q_{2} &                       & \\
    q_{3} &                       & \\
    q_{4} &                       & \\
\end{quantikz}

Thank you!

[ArvinSKushwaha]

Just made a pull request #2843 to hopefully close this issue, I would love to hear any thoughts.

[lervag]

Thanks; I've merged your PR (with a minor fix) now.