Make addCustomEqualityTester available on jasmine global

- User shouldn't have to `jasmine.getEnv()` to add one

[#54582648]

lib/jasmine-core/jasmine.js

@@ -187,6 +187,10 @@ getJasmineRequireObj().base = function(j$) {
     }
     return obj;
   };
+
+  j$.addCustomEqualityTester = function(tester) {
+    j$.getEnv().addCustomEqualityTester(tester);
+  };
 };
 
 getJasmineRequireObj().util = function() {

src/core/base.js

@@ -96,4 +96,8 @@ getJasmineRequireObj().base = function(j$) {
     }
     return obj;
   };
+
+  j$.addCustomEqualityTester = function(tester) {
+    j$.getEnv().addCustomEqualityTester(tester);
+  };
 };