scripts: refactor flash/debug scripts to remove "shell"

The Python-based runners have replaced the old shell scripts. Refactor
the build system accordingly:

- FLASH_SCRIPT is now BOARD_FLASH_RUNNER
- DEBUG_SCRIPT is now BOARD_DEBUG_RUNNER

The values, rather than being the names of files, are now the names of
runners in scripts/support/runner. They are still short, descriptive
names like "openocd", "jlink", "em-starterkit", etc.

Adjust the zephyr_flash_debug.py call and runner internals
accordingly. Have each runner class report a name and the commands it
can handle. This lets us move some boilerplate from each do_run()
method into the common run() routine, and enables further improvements
in future patches.

The handles_command() method is temporary, and will be replaced by a
more general mechanism for describing runner capabilities in a
subsequent patch. The initial use case for extending this is to add
device tree awareness to the runners.

To try to avoid user confusion, abort the configuration if an
xxx_SCRIPT is defined.

Signed-off-by: Marti Bolivar <marti@opensourcefoundries.com>
49 files changed