[Keyboard] Add Support for Wren Keyboard (#14570)

* initial prime_o commit

* Cleaned up comments, other things.

* Updated keymap to use standard seven-underscore KC_TRNS notation

* initial prime_o commit

* Cleaned up comments, other things.

* Updated keymap to use standard seven-underscore KC_TRNS notation

* Initial Code for Wren Keyboard

This is the initial hardware test commit for the wren. More detailed keymaps will be added soon.

* Update layout and add author

* Add PCB Image and Clarify Bootloader Instructions

* Update config.h

Updating config.h to remove mentions to LED backlighting (not supported on this PCB)

* Update wren.h to match PR checklist

* Roll back addition of code that should have been in wren.h

* Update /default/keymap.c

Make keyboard.c "pristine" to the best of my ability and add information about configuring a "non-standard" layout.

* Update readme.md

* Update keymap readmes to match PR checklist

* Update readme.md

* Final touches before PR

* Un-delete non-wren files

* Create rules.mk

* Create config.h

* Update keyboards/wren/keymaps/walterhanley/keymap.c

* Update keyboards/wren/keymaps/walterhanley/keymap.c

* Update keyboards/wren/wren.c

As per feedback, move encoder definition to wren.c from keymap.c.

* Update keyboards/wren/keymaps/walterhanley/keymap.c

As per feedback, move encoder definition to wren.c from keymap.c

* Update keyboards/wren/keymaps/default/keymap.c

As per feedback, move encoder definition to wren.c from keymap.c

* Create Keymap-Level config.h

I've been dealing with some issues with this board over-drawing power on certain devices; this should fix that issue on my build without affecting other users.

* Add bells and whistles to personal keymap

This update adds bells and whistles to my personal keymap. I couldn't figure out how to modify rotary encoder functionality for just my personal layout with the definition in wren.c, so I moved it back into the individual keymaps. Please let me know if this is an issue and I can look into possible alternative implementations.

* Update to match drashna's requested changes

* Update keymap.c

This update refines drashna's requested changes.

* Update keymap.c

Fix typo

keyboards/wren/rules.mk

@@ -0,0 +1,21 @@
+# MCU name
+MCU = atmega32u4
+
+# Bootloader selection
+BOOTLOADER = atmel-dfu
+
+# Build Options
+#   change yes to no to disable
+#
+BOOTMAGIC_ENABLE = yes      # Enable Bootmagic Lite
+MOUSEKEY_ENABLE = yes       # Mouse keys
+EXTRAKEY_ENABLE = yes       # Audio control and System control
+CONSOLE_ENABLE = no         # Console for debug
+COMMAND_ENABLE = no         # Commands for debug and configuration
+# if this doesn't work, see here: https://github.com/tmk/tmk_keyboard/wiki/FAQ#nkro-doesnt-work
+NKRO_ENABLE = no            # USB Nkey Rollover
+BACKLIGHT_ENABLE = no       # Enable keyboard backlight functionality
+RGBLIGHT_ENABLE = no        # Enable keyboard RGB underglow
+AUDIO_ENABLE = no           # Audio output
+ENCODER_ENABLE = yes       # Enables the use of one or more encoders
+SPLIT_KEYBOARD = yes       # Enables split keyboard