core: Add clang-tidy (#8664)

This adds a .clang-tidy file for us.

It's not a strict requirement to be compliant, but I tuned it to be alright.

src/helpers/Monitor.hpp

@@ -16,7 +16,7 @@
 #include <aquamarine/allocator/Swapchain.hpp>
 
 // Enum for the different types of auto directions, e.g. auto-left, auto-up.
-enum eAutoDirs {
+enum eAutoDirs : uint8_t {
     DIR_AUTO_NONE = 0, /* None will be treated as right. */
     DIR_AUTO_UP,
     DIR_AUTO_DOWN,