feat(converter): support figure and tabular environments

[OrangeX4]

basic support for figure, table and tabular environments.

#mitext(`
  \begin{table}[ht]
      \centering
      \begin{tabular}{|c|c|}
          \hline
          \textbf{Name} & \textbf{Age} \\
          \hline
          John & 25 \\
          Jane & 22 \\
          \hline
      \end{tabular}
      \caption{This is an example table.}
      \label{tab:example}
  \end{table}
`)

[Myriad-Dreamin]

Looks pretty well 🎉