feat and refactor: Added mult_size_t_safe and changed how new capacity is calculated for an arena

I wanted to separate things but i was getting confused on how exactly to do it
so i did the best i could, just multiply everithing by 2 and if it overflows then
well, return error, should be enough for most cases to be honest

include/arena.h

@@ -8,7 +8,7 @@
 
 typedef struct {
     uint8_t *buffer;
-    size_t size;
+    size_t capacity;
     size_t offset;
 } Arena;
 
@@ -19,6 +19,7 @@ typedef enum {
     ARENA_NULL_ARG,
     ARENA_INVALID_SIZE,
     ARENA_INVALID_ALIGN,
+    ARENA_CAPACITY_OVERFLOW,
 } ArenaErr;
 
 typedef struct {
@@ -45,14 +46,17 @@ typedef struct {
     };
 } SizeResult;
 
-ArenaResult arena_init(size_t size);
+ArenaResult arena_init(size_t capacity);
 void arena_destroy(Arena *arena);
 
 ArenaPointer arena_alloc(Arena *arena, size_t size, size_t alignment);
 ArenaErr arena_push(Arena *arena, void *data, size_t size, size_t alignment);
-ArenaErr arena_realloc(Arena *arena, size_t new_size);
+ArenaErr arena_realloc(Arena *arena, size_t new_capacity);
 
 SizeResult align_arena_offset(Arena *arena, size_t alignment);
-SizeResult arena_compute_necessary_capacity(size_t capacity, size_t elem_size);
+
+// Should be moved to something like general utilities,
+// i should make one for all my c projects
+bool mul_size_t_safe(size_t a, size_t b, size_t *out);
 
 #endif // !ARENA_H