Catch and abort illegal parallel PC/SC requests early

[emaxx-google]

The PC/SC API requires that every thread of the application uses its own context:

Each thread of an application shall use its own SCARDCONTEXT, unless calling SCardCancel(), which MUST be called with the same context as the context used to call SCardGetStatusChange().

(https://pcsclite.apdu.fr/api/group__API.html#gaa1b8970169fd4883a6dc4a8f43f19b67)

Our implementation in the Smart Card Connector app retains this requirement. However, it's not currently enforced by the client-side libraries that we provide (neither JS nor C++ ones), which means that it can be violated without the developer being notified about that.

Practically, violating this requirement - e.g., sending a new PC/SC call before the previous one with the same hContext finished - can cause bad effects, like the calls being hung. Also - although not confirmed yet - it might lead to the hang of the Smart Card Connector app.

The proposal is to add debug assertions into our C++ and/or JS libraries that would catch these kinds of violations. Perhaps, crashing the caller is the only reasonable and effective measure in that case (note that typical clients would automatically restart after the crash, which hopefully will recover the state and let the user continue using the smart card).

As a stretch goal, we might want to investigate whether/why the Smart Card Connector app hangs for all clients in this scenario, and when that's the case try to fix that behavior.