Pre-hook is not applicable to exercise environment about xsim

[muzimuzhi]

It seems the support for hook options pre-hook, begin-hook, end-hook, and post-hook are incomplete.

For exercise environment, it currently treats all env options as properties. But hook options are not properties, thus they are either ignored (in v0.21 2022/02/12) or throw errors

! Package xsim Error: You tried to set the property `pre-hook' on line <n>.
(xsim)                This property does not exist. Check for a typo or 
(xsim)                define the property yourself.

using the current dev (99d8b80, the change in \__xsim_set_property:nnnn).

For solution environment, it currently process env options through normal key-value functions. This may seem to work if solution envs are printed immediately, but if they're printed by \printsolutions, per env hook settings are still lost.

\documentclass{article}
\usepackage{xsim}

\xsimsetup{
%  solution/print=true
}

\xsimsetup{
  exercise/pre-hook   = {\noindent (pre-exer)},
  exercise/begin-hook = {(begin-exer)},
  exercise/end-hook   = {(end-exer)},
  exercise/post-hook  = {\noindent (post-exer)},
  solution/pre-hook   = {\noindent (pre-solu)},
  solution/begin-hook = {(begin-solu)},
  solution/end-hook   = {(end-solu)},
  solution/post-hook  = {\noindent (post-solu)}
}

\begin{document}

\begin{exercise}[
  pre-hook={\noindent (\textbf{special-pre-exer})},
  begin-hook=(\textbf{special-begin-exer})%
]
  exercise 1
\end{exercise}

\begin{solution}[
  pre-hook={\noindent (\textbf{special-pre-solu})},
  begin-hook=(\textbf{special-begin-solu})
]
  solution 1
\end{solution}

\begin{exercise}
  exercise 1
\end{exercise}

\begin{solution}
  solution 2
\end{solution}

\printsolutions

\end{document}

Using xsim v0.21,

solution/print=true	solution/print=false