Validate if received `acceptedConnectionsHardLimit` is not too large

The number of file descriptors per process can be obtained with [`getrlimit`](https://man7.org/linux/man-pages/man2/getrlimit.2.html) on `Linux` and `MacOS` ([`getrlimit`](https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getrlimit.2.html)) as well as `BSD` ([`getrlimit`](https://man.freebsd.org/cgi/man.cgi?query=getrlimit&sektion=2&format=html)).

We also need to know an upper bound for file descriptors per outbound / inbound (/ duplex) connections used by the consensus layer.

I am not sure how to do that on `Windows`, but maybe we don't need this check there (we don't advise to run relays / BPs on Windows machines).

This issue subsumes #1836.