runtime(tex): add amsmath support to tex syntax script

Problem:  tex syntax file does not support some of the math equation
          environments provided by amsmath.sty, therefore well-formed
          snippet is highlighted as "texBadMath"
Solution: add the environments

closes: #18433

Signed-off-by: Eisuke Kawashima <e-kwsm@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/syntax/testdir/input/tex_03.tex

@@ -0,0 +1,11 @@
+\documentclass{article}
+\usepackage{amsmath}
+\begin{document}
+\begin{align}
+	\begin{bmatrix}
+		1 & x & x^{2} \\
+		1 & y & y^{2} \\
+		1 & z & z^{2} \\
+	\end{bmatrix}
+\end{align}
+\end{document}