refactor: Add more checks to pre-commit

Updated existing pre-commit hooks and added some new hooks:

- Remove trailing whitespace
- Ensure every non-empty file ends with a new line
- Check YAML file validity
- Prevent adding large files
- Ensure any scripts with shebangs are executable

Added a GitHub action to run pre-commit on every commit. Removed any
existing actions which duplicate pre-commit.

Ran pre-commit on the codebase.

app/tests/modifiers/implicit/kp-mod1-dn-mod2-dn-mod1-up-mod2-up/native_posix_64.keymap

@@ -5,10 +5,10 @@
 
 &kscan {
 	events = <
-		ZMK_MOCK_PRESS(0,1,10) 
-		ZMK_MOCK_PRESS(0,0,10) 
+		ZMK_MOCK_PRESS(0,1,10)
+		ZMK_MOCK_PRESS(0,0,10)
 		ZMK_MOCK_RELEASE(0,1,10)
-		ZMK_MOCK_RELEASE(0,0,10) 
+		ZMK_MOCK_RELEASE(0,0,10)
 	>;
 };
 

app/tests/modifiers/implicit/kp-mod1-dn-mod2-dn-mod1-up-mod2-up/pending

@@ -1,9 +1,9 @@
-This test fails because the hid_listener_keycode_released function 
+This test fails because the hid_listener_keycode_released function
 releases implicit modifiers always, even if they were not set by the
 key that's going up. Also see the comment in that function:
 
     If LC(A) is pressed, then LS(B), then LC(A) is released, the shift for B will be released
     prematurely. This causes if LS(B) to repeat like Bbbbbbbb when pressed for a long time.
     Solving this would require keeping track of which key's implicit modifiers are currently
-    active and only releasing modifiers at that time. 
+    active and only releasing modifiers at that time.
 

app/tests/modifiers/implicit/kp-mod1-dn-mod2-dn-mod2-up-mod1-up/native_posix_64.keymap

@@ -5,10 +5,10 @@
 
 &kscan {
 	events = <
-		ZMK_MOCK_PRESS(0,0,10) 
-		ZMK_MOCK_PRESS(0,1,10) 
+		ZMK_MOCK_PRESS(0,0,10)
+		ZMK_MOCK_PRESS(0,1,10)
 		ZMK_MOCK_RELEASE(0,1,10)
-		ZMK_MOCK_RELEASE(0,0,10) 
+		ZMK_MOCK_RELEASE(0,0,10)
 	>;
 };