This may seem like overkill for a mere const char * config item, but it makes
the Control interface VTY commands reusable in any main() scope (inspired by
libosmo-abis' VTY config).
Add API functions ctrl_vty_init() and ctrl_vty_get_bind_addr(), in new files
src/ctrl/control_vty.c and include/osmocom/ctrl/control_vty.h, compiled and/or
installed dependent on ENABLE_VTY.
Using these functions allows configuring a static const char* with the VTY
commands
ctrl
bind A.B.C.D
which callers shall subsequently use to bind the Control interface to a
specific local interface address, by passing the return value of
ctrl_vty_get_bind_addr() to control_interface_setup().
Add CTRL_NODE to enum node_type, "eating" RESERVED4_NODE to heed that comment
on avoiding ABI changes.
