backend/ise: generate detailed map report

This is often of interest and creates little overhead,
so make it unconditionally generated.
add simple bash-completion script for fusesoc

Only the most basic commands are handled, but at least
it fetches the available cores/systems and allows for
autocompletion amongst them.

Further improvements would be to recognize sub-options.
(for instance, the common --elf-load should be easy to
implement as a file completion)