LaTeX reader: put contents of unknown environments in a Div...

when `raw_tex` is not enabled. (When `raw_tex` is enabled,
the whole environment is parsed as a raw block.)
The class name is the name of the environment.
Previously, we just included the contents without the
surrounding Div, but having a record of the environment's
boundaries and name can be useful.

Closes #6997.

src/Text/Pandoc/Readers/LaTeX.hs

@@ -1835,7 +1835,7 @@ rawEnv name = do
        report $ SkippedContent beginCommand pos1
        pos2 <- getPosition
        report $ SkippedContent ("\\end{" <> name <> "}") pos2
-       return bs
+       return $ divWith ("",[name],[]) bs
 
 rawVerbEnv :: PandocMonad m => Text -> LP m Blocks
 rawVerbEnv name = do