feat: add trigonometric methods and Num.pi constant to core library

Add acos, asin, atan, atan2, tan methods to Num class and expose Num.pi constant with value π. Include corresponding C primitives in wren_core.c and test files for each new method.

test/core/number/acos.wren

@@ -0,0 +1,3 @@
+IO.print(0.acos)        // expect: 1.5707963267949
+IO.print(1.acos)        // expect: 0
+IO.print((-1).acos)     // expect: 3.1415926535898

test/core/number/asin.wren

@@ -0,0 +1,3 @@
+IO.print(0.asin)        // expect: 0
+IO.print(1.asin)        // expect: 1.5707963267949
+IO.print((-1).asin)     // expect: -1.5707963267949

test/core/number/atan.wren

@@ -0,0 +1,2 @@
+IO.print(0.atan)        // expect: 0
+IO.print(1.atan)        // expect: 0.78539816339745

test/core/number/atan2.wren

@@ -0,0 +1,4 @@
+IO.print(0.atan(0))     // expect: 0
+IO.print(0.atan(1))     // expect: 0
+
+IO.print(1.atan(0))     // expect: 1.5707963267949

test/core/number/cos.wren

@@ -0,0 +1,6 @@
+IO.print(0.cos)             // expect: 1
+IO.print(Num.pi.cos)        // expect: -1
+IO.print((2 * Num.pi).cos)  // expect: 1
+
+// this should of course be 0, but it's not that precise
+IO.print((Num.pi / 2).cos)  // expect: 6.1232339957368e-17

test/core/number/sin.wren

@@ -0,0 +1,6 @@
+IO.print(0.sin)             // expect: 0
+IO.print((Num.pi / 2).sin)  // expect: 1
+
+// these should of course be 0, but it's not that precise
+IO.print(Num.pi.sin)        // expect: 1.2246467991474e-16
+IO.print((2 * Num.pi).sin)  // expect: -2.4492935982947e-16

test/core/number/tan.wren

@@ -0,0 +1,3 @@
+IO.print(0.tan)             // expect: 0
+IO.print((Num.pi / 4).tan)  // expect: 1
+IO.print((-Num.pi / 4).tan) // expect: -1