x/net/http2: add DialTLSContext to Transport

[Dreamacro]

net.Transport contains DialContext, but http2.Transport only contains DialTLS, so a similar DialTLSContext has been added to make http.Transport support context.

What's changed:

https://github.com/golang/net/blob/8e4df14915a2b0bef8fb1a2d5f67f1bcedc6ab31/http2/transport.go#L66-L88

This proposal only adds a new API, so there is no breaking change.

ref:
golang/net#123
https://go-review.googlesource.com/c/net/+/377114

[ianlancetaylor]

CC @neild @bradfitz

[rsc]

It seems like we clearly need DialTLSContext given that it's already in http.Transport.

[rsc]

Based on the discussion above, this proposal seems like a likely accept.
— rsc for the proposal review group

[rsc]

No change in consensus, so accepted. 🎉
This issue now tracks the work of implementing the proposal.
— rsc for the proposal review group

[francislavoie]

FYI #50392 is a duplicate (rather, was written first, but the PR and this issue were written after without linking to it)

[gopherbot]

Change https://go.dev/cl/377114 mentions this issue: http2: add DialTLSContext to Transport