Rename board from ews_board to ews and fix board discovery

- Rename board directory: ews_board -> ews
- Rename board files: ews_board.dts -> ews.dts, ews_board_defconfig -> ews_defconfig
- Update board identifier and compatible strings
- Add board.cmake for runner configuration
- Set BOARD_ROOT in CMakeLists.txt to enable custom board discovery
- Update all documentation with new board name: west build -b ews

firmware/canfd_cdc_composite/boards/arm/ews/board.cmake

@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: Apache-2.0
+
+if(CONFIG_BOARD_EWS)
+  board_runner_args(jlink "--device=STM32G0B1KB" "--speed=4000")
+  board_runner_args(pyocd "--target=stm32g0b1kbux")
+  
+  include(${ZEPHYR_BASE}/boards/common/pyocd.board.cmake)
+  include(${ZEPHYR_BASE}/boards/common/jlink.board.cmake)
+  include(${ZEPHYR_BASE}/boards/common/openocd.board.cmake)
+endif()