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/ip_common.yaml

@@ -0,0 +1,6 @@
+# Copyright (c) 2024 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+properties:
+  track-remainders:
+    type: boolean

app/dts/bindings/input_processors/ip_one_param.yaml

@@ -0,0 +1,13 @@
+# Copyright (c) 2024 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+include: ip_common.yaml
+
+properties:
+  "#input-processor-cells":
+    type: int
+    required: true
+    const: 1
+
+input-processor-cells:
+  - param1

app/dts/bindings/input_processors/ip_two_param.yaml

@@ -0,0 +1,14 @@
+# Copyright (c) 2024 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+include: ip_common.yaml
+
+properties:
+  "#input-processor-cells":
+    type: int
+    required: true
+    const: 2
+
+input-processor-cells:
+  - param1
+  - param2

app/dts/bindings/input_processors/ip_zero_param.yaml

@@ -0,0 +1,10 @@
+# Copyright (c) 2024 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+include: ip_common.yaml
+
+properties:
+  "#input-processor-cells":
+    type: int
+    required: true
+    const: 0

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

app/dts/bindings/input_processors/zmk,input-processor-scaler.yaml

@@ -0,0 +1,16 @@
+# Copyright (c) 2024, The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+description: Input Processor for scaling values
+
+compatible: "zmk,input-processor-scaler"
+
+include: ip_two_param.yaml
+
+properties:
+  type:
+    type: int
+    required: true
+  codes:
+    type: array
+    required: true

app/dts/bindings/input_processors/zmk,input-processor-temp-layer.yaml

@@ -0,0 +1,21 @@
+# Copyright (c) 2024, The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+description: Input Processor for temporarily enabling a layer after input events
+
+compatible: "zmk,input-processor-temp-layer"
+
+include: ip_two_param.yaml
+
+properties:
+  require-prior-idle-ms:
+    type: int
+    required: false
+    default: 0
+    description: Time in milliseconds that must pass after the last keystroke before the layer can be toggled
+
+  excluded-positions:
+    type: array
+    required: false
+    default: []
+    description: Array of key positions that will NOT trigger layer deactivation when pressed

app/dts/bindings/input_processors/zmk,input-processor-transform.yaml

@@ -0,0 +1,18 @@
+# Copyright (c) 2024, The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+description: Input Processor for transforming values in various ways
+
+compatible: "zmk,input-processor-transform"
+
+include: ip_one_param.yaml
+
+properties:
+  type:
+    type: int
+  x-codes:
+    type: array
+    required: true
+  y-codes:
+    type: array
+    required: true