MailReaderSampler - implement connection and socket timeouts?

**Sebb** ([Bug 56432](https://bz.apache.org/bugzilla//show_bug.cgi?id=56432&redirect=false)):
Might be useful to implement connection and socket timeouts, i.e.

mail.{protocol}.connectiontimeout
mail.{protocol}.timeout

OS: All

Start by locating MailReaderSampler and the mail.{protocol}.connectiontimeout and mail.{protocol}.timeout properties referenced in the issue. Trace how the sampler establishes its connection and reads from the socket, then confirm both timeout settings are honored across the supported mail protocols.

Written by the indexing model from the issue text.