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/dumps/tex_03_00.dump

@@ -0,0 +1,20 @@
+>\+0#af5f00255#ffffff0|d|o|c|u|m|e|n|t|c|l|a|s@1|{+0#e000e06&|a|r|t|i|c|l|e|}| +0#0000000&@51
+|\+0#af5f00255&|u|s|e|p|a|c|k|a|g|e|{+0#e000e06&|a|m|s|m|a|t|h|}| +0#0000000&@54
+|\+0#e000e06&|b|e|g|i|n|{|d|o|c|u|m|e|n|t|}| +0#0000000&@58
+|\+0#af5f00255&|b|e|g|i|n|{+0#e000e06&|a|l|i|g|n|}| +0#0000000&@61
+| +0#e000e06&@7|\+0#af5f00255&|b|e|g|i|n|{+0#e000e06&|b|m|a|t|r|i|x|}| +0#0000000&@51
+| +0#e000e06&@15|1| |&| |x| |&| |x|^|{|2+0#af5f00255&|}+0#e000e06&| |\@1| +0#0000000&@42
+| +0#e000e06&@15|1| |&| |y| |&| |y|^|{|2+0#af5f00255&|}+0#e000e06&| |\@1| +0#0000000&@42
+| +0#e000e06&@15|1| |&| |z| |&| |z|^|{|2+0#af5f00255&|}+0#e000e06&| |\@1| +0#0000000&@42
+| +0#e000e06&@7|\+0#af5f00255&|e|n|d|{+0#e000e06&|b|m|a|t|r|i|x|}| +0#0000000&@53
+|\+0#af5f00255&|e|n|d|{+0#e000e06&|a|l|i|g|n|}| +0#0000000&@63
+|\+0#e000e06&|e|n|d|{|d|o|c|u|m|e|n|t|}| +0#0000000&@60
+|~+0#4040ff13&| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+| +0#0000000&@56|1|,|1| @10|A|l@1| 

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}