common: Add function for checking word alignment to alignment.h

This will be used in a following change to svcArbitrateLock() and
svcArbitrateUnlock()

src/common/alignment.h

@@ -25,4 +25,10 @@ constexpr bool Is4KBAligned(T value) {
     return (value & 0xFFF) == 0;
 }
 
+template <typename T>
+constexpr bool IsWordAligned(T value) {
+    static_assert(std::is_unsigned_v<T>, "T must be an unsigned value.");
+    return (value & 0b11) == 0;
+}
+
 } // namespace Common