frontends: prefix frontends with 'kconfig-'

frontends: prefix frontends with 'kconfig-'

By default, prefix the frontends executables with 'kconfig-'
to avoid any name-space collision ('conf' is too generic).

At the same time, prefix all libraries with kconfig-, for
consistency (except libkconfig-parser, which only gains a
dash in-between 'kconfig' and 'parser').

Besides, utilities (coming in a following cset) will all be
prefixed with 'kconfig-' to avoid name-space collision, too.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>