LaTeX reader: improve mathEnvWith.

When converting e.g. an align environment to an aligned environment
inside a Math element, we need to include a newline before the
`\end{aligned}`, since the previous line might end in a comment.

Closes #8122.

src/Text/Pandoc/Readers/LaTeX/Math.hs

@@ -65,7 +65,7 @@ mathEnvWith f innerEnv name = f . mathDisplay . inner <$> mathEnv name
    where inner x = case innerEnv of
                         Nothing -> x
                         Just y  -> "\\begin{" <> y <> "}\n" <> x <>
-                                   "\\end{" <> y <> "}"
+                                   "\n\\end{" <> y <> "}"
 
 mathEnv :: PandocMonad m => Text -> LP m Text
 mathEnv name = do

test/command/3113.md

@@ -11,7 +11,7 @@ E&=&F
 [ Para
     [ Math
         DisplayMath
-        "\\begin{aligned}\nA&=&B,\\\\\nC&=&D,\\\\\n%\\end{eqnarray}\n%\\begin{eqnarray}\nE&=&F\\end{aligned}"
+        "\\begin{aligned}\nA&=&B,\\\\\nC&=&D,\\\\\n%\\end{eqnarray}\n%\\begin{eqnarray}\nE&=&F\n\\end{aligned}"
     ]
 ]
 ```

test/command/macros.md

@@ -62,7 +62,8 @@ x &= y\\
 \(5-67\)
 
 \[\begin{aligned}
-x &= y\\\end{aligned}\]
+x &= y\\
+\end{aligned}\]
 
 \emph{hi}