feat(assert): add general assertion that always executes its condition

Its purpose is used to check the value of conditions whose sideeffects are
critical to the program.
this makes it possible to avoid code such as
```cpp
[[maybe_unused]] bool successful = moveToThread(m_pThread.get());
DEBUG_ASSERT(successful);
```
and instead write
```cpp
ASSERT(moveToThread(m_pThread.get()));
```

src/util/assert.h

@@ -24,6 +24,10 @@ inline void mixxx_release_assert(const char* assertion, const char* file, int li
     qFatal("ASSERT: \"%s\" in function %s at %s:%d", assertion, function, file, line);
 }
 
+inline void mixxx_assert(const char* assertion, const char* file, int line, const char* function) {
+    qWarning("ASSERT: \"%s\" in function %s at %s:%d", assertion, function, file, line);
+}
+
 // These macros provide the demangled function name (including helpful template
 // type information) and are supported on every version of GCC, Clang, and MSVC
 // that Mixxx supports.
@@ -44,6 +48,26 @@ inline void mixxx_release_assert(const char* assertion, const char* file, int li
         }                                                                     \
     while (0)
 
+/// Checks that cond is true. If cond is false then prints a warning message
+/// but does not quit.
+/// Its purpose is used to check the value of conditions whose sideeffects are
+/// critical to the program.
+// this makes it possible to avoid code such as
+// ```cpp
+// [[maybe_unused]] bool successful = moveToThread(m_pThread.get());
+// DEBUG_ASSERT(successful);
+// ```
+// and instead write
+// ```cpp
+// ASSERT(moveToThread(m_pThread.get()));
+// ```
+#define ASSERT(cond)                                                  \
+    do                                                                \
+        if (!static_cast<bool>(cond)) [[unlikely]] {                  \
+            mixxx_assert(#cond, __FILE__, __LINE__, ASSERT_FUNCTION); \
+        }                                                             \
+    while (0)
+
 /// Checks that cond is true in debug builds. If cond is false then prints a
 /// warning message to the console. If Mixxx is built with
 /// MIXXX_DEBUG_ASSERTIONS_FATAL then the warning message is fatal. Compiles