This commit de-duplicates the redundant dummy implementations and
to some degree also the 'lx_emul.c' implementations while also
decluttering the various 'dep.list' files.
The code is moved into 'src/lib/pc/lx_emul' where it becomes part
of the 'pc_lx_emul' library.
Fixes#4500.
The driver falls in line with the previous 'legacy_wifi_drv' component
where the ported wireless LAN stack and device driver is encapsulated
in a library. This library in return is used by the 'Libc::Component'
providing the necessary environment for the 'wpa_supplicant'.
In constrast to the old driver a 'wifi' VFS plugin is in charge of
initalizing the 'Lx_kit::Env' prior to executing any static
constructors.
Fixes#4455.
