Add Razer BlackWidow 2019 keyboard

[htv04]

Description

Depends on #26327.

This PR adds support for the Razer BlackWidow 2019, a full-size ANSI keyboard built on an STM32L151RCT6. Everything was tested on unmodified hardware.

Matrix pinout, keymap, and IS31FL3733 layout were reverse-engineered. The RGB matrix includes the five indicator LEDs and the logo. The lock indicators mirror host lock state as normal, the "Game" LED is repurposed for GUI lock, and the "Macro" LED for dynamic macro recording.

The default keymap follows the stock Fn legends, with some modifications (see README).

The stock Razer bootloader can't flash QMK directly, so installation goes through the STM32 ROM DFU instead, following the steps from the razer-qmk project (also referenced in the README). Once installed, the ROM bootloader is entered via bootmagic (Escape by default).

Types of Changes

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

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).

[drashna]

Strictly speaking, you don't actually need to add support to core for the board to work.

For reference, this is for an F429, which isn't officially supported by the repo:
https://github.com/drashna/qmk_firmware/tree/custom_drashna/keyboards/handwired/tractyl_manuform/5x6_right/f429_waveshare

I can confirm that it compiles and works. You may want to do something like this rather than full implementation

[htv04]

I considered that approach, but I went with a full generic board implementation because I know of other Razer boards that also have an onboard STM32 from around the timeframe the Razer BlackWidow 2019 was released (even a few STM32 BOOTLOADER posts in the Razer forums). They most likely use the same MCU, maybe even the same interface, so this approach would make it easier to implement such boards in the future.