We have multiple situations where we have a `net.Conn` representing a
TCP connection for a proxy and we need access to the underlying
`CloseWrite()` and `CloseRead()` functions to properly pass through
half-closes (see #16462, #20883). Add an interface we can cast to in
order to get access to these functions.
Updates #20883.
Signed-off-by: Naman Sood <mail@nsood.in>
Naman Sood
35848427ce