[Keyboard] add Boston keyboard (#11273)

* Added boston keyboard

* Added Boston keyboard

* Changed some keycodes, added layers, added encoder layer change, added RGB layer indicator

* Cleaned up whitespace

* Update config.h

Cleaned up whitespace

* Cleaned up whitespace

* Added keyboard_post_init_kb code for RGBLEDs so that they start on a defined color

* Modified layout so that split backspace right is at a more intuitive location for configurator

* Cleaned up whitespace, changed some labels

* Modified keymap to accommodate revised layout in boston.h

* Removed "on port C6" from Line 20 (committed suggestion)

* Removed "Encoder Enable" from Line 8 (committed suggestion)

* Removed empty #define DESCRIPTION as suggested

* Implemented lock LED changes as suggested by drashna

* Implemented lock LED changes as suggested by Drashna, changed WS2812 driver byte order

* Updated HSV color  codes to reflect WS2812 byte order change

* Implemented suggestion from noroadsleft

* Implemented suggestion from noroadsleft

* Updated readm.md per suggestions from noroadsleft

* Update keyboards/boston/readme.md per noroadsleft's suggestion

* Removed empty layers from default keymap

* Stripped empty layers and much code from default keymap ; moved to RGB Light Layers keycap

keyboards/boston/rules.mk

@@ -0,0 +1,26 @@
+# MCU name
+MCU = STM32F072
+
+# Build Options
+#   change yes to no to disable
+#
+BOOTMAGIC_ENABLE = yes     # Virtual DIP switch configuration
+MOUSEKEY_ENABLE = no       # Mouse keys
+EXTRAKEY_ENABLE = yes      # Audio control and System control
+CONSOLE_ENABLE = no        # Console for debug
+COMMAND_ENABLE = no        # Commands for debug and configuration
+# Do not enable SLEEP_LED_ENABLE. it uses the same timer as BACKLIGHT_ENABLE
+SLEEP_LED_ENABLE = no      # Breathing sleep LED during USB suspend
+# if this doesn't work, see here: https://github.com/tmk/tmk_keyboard/wiki/FAQ#nkro-doesnt-work
+NKRO_ENABLE = yes          # USB Nkey Rollover
+BACKLIGHT_ENABLE = yes     # Enable keyboard backlight functionality
+RGBLIGHT_ENABLE = yes      # Enable keyboard RGB underglow
+BLUETOOTH_ENABLE = no      # Enable Bluetooth
+AUDIO_ENABLE = no          # Audio output
+ENCODER_ENABLE = yes
+
+# Enter lower-power sleep mode when on the ChibiOS idle thread
+OPT_DEFS += -DCORTEX_ENABLE_WFI_IDLE=TRUE
+
+# RGB setting
+WS2812_DRIVER = bitbang