[FEATURE] Set SocketOpts

[Bibo-Joshi]

To improve the networking backend, we would like to set socketopts if possible. Before the asyncio switch, we did something like

python-telegram-bot/telegram/request/_httpxrequest.py

Lines 164 to 168 in ad5a1fb

	# TODO p0: On Linux, use setsockopt to properly set socket level keepalive.
	# (socket.IPPROTO_TCP, socket.TCP_KEEPIDLE, 120)
	# (socket.IPPROTO_TCP, socket.TCP_KEEPINTVL, 30)
	# (socket.IPPROTO_TCP, socket.TCP_KEEPCNT, 8)
	# TODO p4: Support setsockopt on lesser platforms than Linux.

It would be nice if we could do that for httpx as well at some point.

[Bibo-Joshi]

httpx v0.25.0 added support for socket_options in encode/httpx#2716. The underlying change is encode/httpcore#668 and some documentation can be found here and here.
This might give us a handle to add support for socket options as well. CC @tsnoam