math: Add trigonometric functions and some angle helper functions

This commit adds these new template functions in the `math` namespace:

math.Acos
math.Asin
math.Atan
math.Atan2
math.Cos
math.Pi
math.Sin
math.Tan
math.ToDegrees
math.ToRadians

Co-authored-by: Joe Mooring <joe@mooring.com>

docs/content/en/functions/math/ToDegrees.md

@@ -0,0 +1,19 @@
+---
+title: math.ToDegrees
+description: ToDegrees converts radians into degrees.
+categories: []
+keywords: []
+action:
+  aliases: []
+  related:
+    - functions/math/ToRadians
+    - functions/math/Pi
+  returnType: float64
+  signatures: [math.ToDegrees VALUE]
+---
+
+{{< new-in 0.130.0 >}}
+
+```go-html-template
+{{ math.ToDegrees 1.5707963267948966 }} → 90
+```