Support mixed boxed and unboxed primitives in assertEquals()

Prior to this commit, the following resulting in a compiler error due to
ambiguity.

    assertEquals(42, Integer.valueOf("42"));

The same holds true for all primitive types other than `boolean`.

This commit addresses this shortcoming by introducing assertEquals()
variants that support mixed boxed and unboxed primitive values.

Issue: #1638

Author: sbrannen

documentation/src/docs/asciidoc/release-notes/release-notes-5.4.0-M1.adoc

@@ -54,6 +54,9 @@ repository on GitHub.
 
 ==== New Features and Improvements
 
+* New `Assertions.assertEquals()` variants that accept mixed boxed and unboxed primitive
+  values, allowing statements such as `assertEquals(42, Integer.valueOf("42"))` to
+  compile.
 * New `Assertions.assertNotEquals()` variants that accept the following primitive data
   types: `char`, `byte`, `short`, `int`, `long`, `float`, and `double`.
 * Implicit conversion from hexadecimal and octal string representations to integral types