add ipad power and home keycodes

[stillinbeta]

Description

Based on Apple's Accessory Design Guidelines the iPad uses a couple keycodes from the Consumer range of the HID spec.

Most of these codes are already covered or not useful, but Power and Home are extremely so.

I've added the following keycodes:

Key	Aliases	Description	QMK Keycode	Consumer page keycode
KC_IPAD_POWER	KC_IPWR	Power button in iPadOS	0x00C3	0x30
KC_IPAD_HOME	KC_IHOM	Home button on iPadOS	0x00C4	0x40

Based on the precedent of KS_LAUNCHPAD (#19884) I've named them according to their current only-known use. I think a more accurate title like KC_CONSUMER_POWER would just be confusing.
If these keys have other uses, nobody has needed them in QMK so far.

This also changes the values of CONSUMER_KEYCODE_RANGE, as I've placed my keycodes after the existing Launchpad PR.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout (addition or update)
• Documentation

Issues Fixed or Closed by This PR

n/a

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).