Currently a card must be present in the reader until the user can enter
pySim-shell. Removing and plugging another card is in theory already
possible, but then the new card will operate on the old card and runtime
state object. It might also be useful to enter pySim-shell before the
card is plugged to execute some other commands for preperation before.
So lets allow to "equip" pySim-shell with a card and rs object at
runtime.
Related: SYS#5617
Change-Id: I9cf532d9da8203065463c7201e7064de6c7ab1b5