ARC: west: mdb runner: change folder to run MDB

Make the build folder the place where MDB is run. Otherwise mdb
will store the .sc.project folder in the place where twister is
launched (so .sc.project folder will be shared across the runs)

For that we add **kwargs argument to popen_ignore_int method
so we can pass a cwd argument to the Popen constructor.

Signed-off-by: Evgeniy Paltsev <PaltsevEvgeniy@gmail.com>
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>