Apply #pragma once, misc cleanup (#12322)

* Apply #pragma once in headers
* Adjust some thermistors formatting
* Misc cleanup and formatting

Marlin/src/feature/filwidth.h

@@ -19,9 +19,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  *
  */
-
-#ifndef __FILWIDTH_H__
-#define __FILWIDTH_H__
+#pragma once
 
 #include "../inc/MarlinConfig.h"
 
@@ -31,5 +29,3 @@ extern float filament_width_nominal,                        // Nominal filament
 extern uint8_t meas_delay_cm;                               // Distance delay setting
 extern int8_t measurement_delay[MAX_MEASUREMENT_DELAY + 1], // Ring buffer to delayed measurement. Store extruder factor after subtracting 100
               filwidth_delay_index[2];                      // Indexes into ring buffer
-
-#endif // __FILWIDTH_H__