remsim-client: allow for local handling of APDUs
During many remote sim use cases, 99% of the SIM card related accesses could be handled locally on the client. Only communication related to cryptographic authentication as well as OTA related bits need to go to the real SIM card.
So the idea of this ticket is to implement some kind of "local proxy" that can run on the client, and which handles [possibly configurable degrees] of features locally.
For sure the entire [lengthy, time-consuming] phonebook and SMS related accesses can be handled locally in most use cases. For other files containing Kc or TMSI it is possible to handle locally. Finally, for things like the IMSI we most certainly always want to go back to the real SIM card and could [if at all] only cache it in the client.