feat(mouse): Add mouse move and scroll support (#2477)

* feat(mouse): Add mouse move and scroll support

    * Use Zephyr input subsystem for all pointers.
    * Input processors for modifying events, e.g. scaling, swapping
      codes, temporary (mouse) layers, etc.
    * Mouse move/scroll behaviors.
    * Infrastructure in place for physical pointer input devices.

* feat: Add input split support.

* docs: Add initial pointer docs.

---------

Co-authored-by: Cem Aksoylar <caksoylar@users.noreply.github.com>
Co-authored-by: Alexander Krikun <krikun98@gmail.com>
Co-authored-by: Robert U <urob@users.noreply.github.com>
Co-authored-by: Shawn Meier <ftc@users.noreply.github.com>
Co-authored-by: Chris Andreae <chris@andreae.gen.nz>
Co-authored-by: Anant Thazhemadam <47104651+thazhemadam@users.noreply.github.com>
Co-authored-by: Erik Tollerud <erik.tollerud@gmail.com>
Co-authored-by: Nicolas Munnich <98408764+Nick-Munnich@users.noreply.github.com>

app/dts/bindings/behaviors/zmk,behavior-input-two-axis.yaml

@@ -0,0 +1,28 @@
+# Copyright (c) 2024 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+description: Two axis input behavior
+
+compatible: "zmk,behavior-input-two-axis"
+
+include: one_param.yaml
+
+properties:
+  x-input-code:
+    type: int
+    required: true
+  y-input-code:
+    type: int
+    required: true
+  trigger-period-ms:
+    type: int
+    default: 16
+    description: The time (in ms) between generated inputs when an input has non-zero speed.
+  delay-ms:
+    type: int
+  time-to-max-speed-ms:
+    type: int
+    required: true
+  acceleration-exponent:
+    type: int
+    default: 1