[Bug] Realign and size check EECONFIG structures (#20541)

Co-authored-by: Nick Brassel <[email protected]>

quantum/unicode/unicode.h

@@ -21,12 +21,14 @@
 #include "quantum.h"
 
 typedef union {
-    uint32_t raw;
+    uint8_t raw;
     struct {
         uint8_t input_mode : 8;
     };
 } unicode_config_t;
 
+_Static_assert(sizeof(unicode_config_t) == sizeof(uint8_t), "Unicode EECONFIG out of spec.");
+
 extern unicode_config_t unicode_config;
 
 enum unicode_input_modes {