style: rename hSocket to sock

Summary:
In the arguments of InterruptibleRecv(), Socks5() and
ConnectThroughProxy() the variable hSocket was previously of type
SOCKET, but has been changed to Sock. Thus rename it to sock to
imply its type, to distinguish from other SOCKET variables and to
abide to the coding style wrt variables' names.

This is a backport of core#20788 [5/5]
https://github.com/bitcoin/bitcoin/pull/20788/commits/7bd21ce1efc363b3e8ea1d51dd1410ccd66820cb

Depends on D11006

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D11007