cmake variables

Here is a lsit of the CMake variables which affect runners and whether they can be converted assuming these criteria.

Totals:

- Y: 9
- N: 27
- ?: 2

- BOSSAC (N): user-settable (e.g. -DBOSSAC=my/special/bossac)
- BOSSAC_PORT (N): user-settable (e.g. -DBOSSAC_PORT=COM3); we wish we could pass this to "make flash"


- DFUUTIL_ALT (Y): board files must set
- DFUUTIL_DFUSE_OPTIONS (N): board- or app-customizable (we normally want to set(DFUUTIL_DFUSE_OPTIONS leave), but I have an mcuboot use case to use "force;mass-erase" instead.)
- DFUUTIL_DFUSE (Y): OK to omit, board files may set
- DFUUTIL_IMG (N): user-settable (e.g. -Dmy-signed-mcuboot-binary.bin -- though this ability should be made more general so it doesn't assume dfu-util)
- DFUUTIL_PID (Y): board files must set


- ESP_BAUD_RATE (N): user-settable, I think (e.g. -DESP_BAUD_RATE=lower_value_for_FTDI_clone)
- ESP_DEVICE (N): user-settable (like BOSSAC_PORT)
- ESP_FLASH_FREQ (?): I don't know what this does
- ESP_FLASH_MODE (?): I don't know what this does
- ESP_FLASH_SIZE (Y): board files must set (I think)
- ESP_IDF_PATH (N): user-settable (export ESP_IDF_PATH=/my/download/location; should not be an env var eventually, but I left it alone since I can't build this board.)
- ESP_TOOL (N): user-settable


- JLINK_GDB_PORT (N): user-settable
- JLINK_GDBSERVER (N): user-settable
- JLINK_IFACE (Y): OK to omit, board files may set
- JLINK_TUI (N): user-settable


- NIOS2_CPU_SOF (N): user-settable
- NIOS2_TUI (N): user-settable


- NRF_FAMILY (Y): board files must set


- OPENOCD_GDB_PORT (N): user-settable
- OPENOCD_LOAD_ADDRESS (N): users or board files may want to customize or override (though DT feels like the usual case)
- OPENOCD_LOAD_BINARY (N): user-settable (like DFUUTIL_IMG, another candidate for unification)
- OPENOCD_LOAD_CMD (and OPENOCD_USE_LOAD_IMAGE) (N): customizable / overridable
- OPENOCD_POST_CMD (Y): OK to omit, board files may provide
- OPENOCD_PRE_CMD (Y): OK to omit, board files may provide
- OPENOCD_TCL_PORT (N): user-settable
- OPENOCD_TELNET_PORT (N): user-settable
- OPENOCD_TUI (N): user-settable
- OPENOCD_VERIFY_CMD (N): customizable / overridable


- PYOCD_BOARD_ID (N): user-settable; we wish we could push this at runtime
- PYOCD_DAPARG (N): user-settable (this was added to give users a workaround for Windows issues)
- PYOCD_FLASHTOOL (N): user-settable
- PYOCD_FLASHTOOL_OPTS (N): user-settable
- PYOCD_GDB_PORT (N): user-settable
- PYOCD_GDBSERVER (N): user-settable
- PYOCD_TUI (N): user-settable