fix: add more test coverage for minArray/maxArray

To cover bug reported on go-jsonnet:
google/go-jsonnet#790

Author: johnbartholomew

test_suite/error.std_maxArray.jsonnet

@@ -0,0 +1 @@
+std.maxArray([])

test_suite/error.std_maxArray.jsonnet.golden

@@ -0,0 +1,4 @@
+RUNTIME ERROR: Expected at least one element in array. Got none
+	std.jsonnet:<stdlib_position_redacted>	thunk <onEmpty>
+	std.jsonnet:<stdlib_position_redacted>	function <anonymous>
+	error.std_maxArray.jsonnet:1:1-17	

test_suite/error.std_minArray.jsonnet

@@ -0,0 +1 @@
+std.minArray([])

test_suite/error.std_minArray.jsonnet.golden

@@ -0,0 +1,4 @@
+RUNTIME ERROR: Expected at least one element in array. Got none
+	std.jsonnet:<stdlib_position_redacted>	thunk <onEmpty>
+	std.jsonnet:<stdlib_position_redacted>	function <anonymous>
+	error.std_minArray.jsonnet:1:1-17	

test_suite/stdlib.jsonnet

@@ -1583,12 +1583,18 @@ std.assertEqual(std.avg([1, 2, 3]), 2) &&
 std.assertEqual(std.avg([0, 0, 0]), 0) &&
 std.assertEqual(std.avg([1, 1, 2.5]), 1.5) &&
 
-std.assertEqual(std.minArray([1, 2, 3]), 1) &&
-std.assertEqual(std.minArray(['1', '2', '3']), '1') &&
+std.assertEqual(std.minArray([3, 1, 2]), 1) &&
+std.assertEqual(std.minArray(['3', '1', '2']), '1') &&
+std.assertEqual(std.minArray(['a2', 'b1'], keyF=function(x) x[0]), 'a2') &&
+std.assertEqual(std.minArray(['a2', 'b1'], keyF=function(x) x[1]), 'b1') &&
+std.assertEqual(std.minArray([], onEmpty='default'), 'default') &&
 
 std.assertEqual(std.maxArray([1, 2, 3]), 3) &&
 std.assertEqual(std.maxArray(['1', '2', '3']), '3') &&
 std.assertEqual(std.maxArray(['a', 'x', 'z']), 'z') &&
+std.assertEqual(std.maxArray(['a2', 'b1'], keyF=function(x) x[0]), 'b1') &&
+std.assertEqual(std.maxArray(['a2', 'b1'], keyF=function(x) x[1]), 'a2') &&
+std.assertEqual(std.maxArray([], onEmpty='default'), 'default') &&
 
 
 std.assertEqual(std.xor(true, false), true) &&