Add connect_from methods to TcpStream

[valaphee]

When having multiple ip addresses assigned, it is not possible to use a specific one when establishing a TCP connection. connect_from solves this allowing to use a specific ip to bind first.

Solves #68053

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[the8472]

As mentioned in #68053 (comment) I think this API is too inflexible for the many ways that sockets can be built up and adding use cases one method at a time will likely lead to bad API design.
Compare to the Socket2 API surface for example.

Imo this requires discussion about the overall design we're aiming for and whether there could be intermediate steps. Filing an ACP could be a start.

[valaphee]

I agree that its to inflexible, and could ultimately be replaced by a more flexible socket api in general.

Isn't there already an ACP for a socket api overhaul?

[the8472]

Oh right, there was a somewhat related request in rust-lang/libs-team#66 which was about unbound UDP sockets.

[JohnCSimon]

@valaphee
Ping from triage: I'm closing this due to inactivity, Please reopen when you are ready to continue with this.
Note: if you are going to continue please open the PR BEFORE you push to it, else you won't be able to reopen - this is a quirk of github.
Thanks for your contribution.

@rustbot label: +S-inactive