fixes#22775
It's pre-existing that [`prepareOperand` doesn't typecheck expressions
which have
types](a4f3bf3742/compiler/sigmatch.nim (L2444)).
Templates can take typed subscript expressions, transform them into
calls to `[]`, and then have this `[]` not be resolved later if the
expression is nested inside of a call argument, which leaks an untyped
expression past semantic analysis. To prevent this, don't transform any
typed subscript expressions into calls to `[]` in templates. Ditto for
curly subscripts (with `{}`) and assignments to subscripts and curly
subscripts (with `[]=` and `{}=`).
