[Keyboard] Add AMJ66 keyboard (#5945)

* Added nearly perfect config for AMJ66, only missing top right key.

* Correct the layout macro

* Add layout mock-up to amj66.h

* Update and comment out the backlight definitions in config.h

The backlight pin was found to be D4, but there appears to be a bug in QMK that affects this keyboard.

Commenting out for now.

* Try to make a sensible default keymap

* Add testing keymap for FSund

Include the keymap that was being used for testing.

Don't forget to refactor this later into an actually useful keymap.

* Suggestions by fauxpark

- uncomment the backlight configuration
- fix the default keymap
- remove commented MCU rule
- specify the bootloader
- make mental note to not try to write code at 3:30 in the morning

* Add LAYOUT_66_ansi and LAYOUT_66_iso macros

- include QMK Configurator data
- enable Community Layout support

* Add comments about layout variants to amj66.h

* Add #define BACKLIGHT_ON_STATE 1

Partial fix for backlight breathing.

- Requires #5983 to fix fully (confirmed by FSund and fauxpark)

Co-Authored-By: fauxpark <fauxpark@gmail.com>
Co-Authored-By: Filip Sund <filip.sund@gmail.com>

* DEBOUNCING_DELAY -> DEBOUNCE

* Move AMJ66 files into new AMJKeyboard directory

* Correct Manufacturer in USB Device Descriptor

* Remove comment regarding source fork

* Correct the readme

* Update default keymap to match the details given in its readme

* White-space edit fsund_test keymap

Makes its formatting more consistent with other 66% keymaps. No logic changes.

* Linting info.json

Debug-style linting (one key object per line) and minor edits to key labels.

* Remove fsund_test keymap

* Add FSund as a maintainer in info.json

1 files changed, 15 insertions, 0 deletions

diff --git a/keyboards/amjkeyboard/amj66/readme.md b/keyboards/amjkeyboard/amj66/readme.md
new file mode 100644
index 0000000000..37a1f27ea6
--- /dev/null
+++ b/keyboards/amjkeyboard/amj66/readme.md
@@ -0,0 +1,15 @@
+# AMJ66
+
+![AMJ66](https://i.imgur.com/qtLuL2o.jpg)
+
+A 66% keyboard formerly sold by Massdrop and KBDFans.
+
+Keyboard Maintainer: [FSund](https://github.com/fsund), [The QMK Community](https://github.com/qmk)  
+Hardware Supported: AMJ66, ATmega32U4  
+Hardware Availability: [Drop.com](https://drop.com/buy/kbd66-mechanical-keyboard-kit?mode=guest_open)
+
+Make example for this keyboard (after setting up your build environment):
+
+    make amjkeyboard/amj66:default
+
+See the [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) and the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information. Brand new to QMK? Start with our [Complete Newbs Guide](https://docs.qmk.fm/#/newbs).