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/input_processors/zmk,input-processor-code-mapper.yaml

@@ -0,0 +1,16 @@
+# Copyright (c) 2024, The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+description: Input Processor for remapping certain input codes to other codes
+
+compatible: "zmk,input-processor-code-mapper"
+
+include: ip_zero_param.yaml
+
+properties:
+  type:
+    type: int
+    required: true
+  map:
+    type: array
+    required: true