Make PREVENT_STUCK_MODIFIERS the default (#3107)

* Remove chording as it is not documented, not used, and needs work.

* Make Leader Key an optional feature.

* Switch from `PREVENT_STUCK_MODIFIERS` to `STRICT_LAYER_RELEASE`

* Remove `#define PREVENT_STUCK_MODIFIERS` from keymaps.

keyboards/planck/keymaps/tehwalris/config.h

@@ -3,8 +3,6 @@
 
 #include "../../config.h"
 
-#define PREVENT_STUCK_MODIFIERS
-
 #ifdef AUDIO_ENABLE
     // #define STARTUP_SONG SONG(PLANCK_SOUND)
     #define STARTUP_SONG SONG(NO_SOUND)
@@ -27,7 +25,7 @@
 /* enable basic MIDI features:
    - MIDI notes can be sent when in Music mode is on
 */
-                                
+
 #define MIDI_BASIC
 
 /* enable advanced MIDI features: