feat(kscan): Improve matrix debouncing

Switched the GPIO matrix driver to debouncing using a simple integrator
algorithm. Whenever a key is pressed, we now scan at a rate controlled
by debounce-scan-period-ms (default 1 ms) until all keys are released,
then return to either waiting for an interrupt or polling more slowly.

The timers for key press and release can now be controlled separately,
so debounce-period is deprecated in favor of debounce-press-ms and
debounce-release-ms. Global Kconfig options
ZMK_KSCAN_DEBOUNCE_PRESS_MS and ZMK_KSCAN_DEBOUNCE_RELEASE_MS are also
added to make these easier to set.

Added documentation for debouncing options.

app/drivers/zephyr/dts/bindings/kscan/zmk,kscan-gpio-matrix.yaml

@@ -15,13 +15,26 @@ properties:
     type: phandle-array
     required: true
   debounce-period:
+    type: int
+    required: false
+    deprecated: true
+    description: Deprecated. Use debounce-press-ms and debounce-release-ms instead.
+  debounce-press-ms:
     type: int
     default: 5
-    description: Debounce time in milliseconds
+    description: Debounce time for key press in milliseconds. Use 0 for eager debouncing.
+  debounce-release-ms:
+    type: int
+    default: 5
+    description: Debounce time for key release in milliseconds.
+  debounce-scan-period-ms:
+    type: int
+    default: 1
+    description: Time between reads in milliseconds when any key is pressed.
   poll-period-ms:
     type: int
     default: 10
-    description: Time between reads in milliseconds when polling is enabled
+    description: Time between reads in milliseconds when no key is pressed and ZMK_KSCAN_MATRIX_POLLING is enabled.
   diode-direction:
     type: string
     default: row2col