Enable Adafruit-GFX-Library as ESP-IDF component support (#376)

Enables Adafruit-GFX-Library as ESP-IDF component support  (with Arduino as component)

CMakeLists.txt

@@ -0,0 +1,11 @@
+# Adafruit GFX Library
+# https://github.com/adafruit/Adafruit-GFX-Library
+# BSD License
+
+cmake_minimum_required(VERSION 3.5)
+
+idf_component_register(SRCS "Adafruit_GFX.cpp" "Adafruit_GrayOLED.cpp" "Adafruit_SPITFT.cpp" "glcdfont.c"
+                       INCLUDE_DIRS "."
+                       REQUIRES arduino Adafruit_BusIO)
+
+project(Adafruit-GFX-Library)

component.mk

@@ -0,0 +1 @@
+COMPONENT_ADD_INCLUDEDIRS = .