add saola button pin support, esp32 build with board_test

examples/device/board_test/CMakeLists.txt

@@ -0,0 +1,14 @@
+# The following five lines of boilerplate have to be in your project's
+# CMakeLists in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.5)
+
+# example src directory
+set(EXTRA_COMPONENT_DIRS "src")
+
+# TOP is absolute path to root directory of TinyUSB git repo
+set(TOP "../../..")
+get_filename_component(TOP "${TOP}" REALPATH)
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+
+project(board_test)