stabilize @std/http

[kt3k]

part of #4600

• fully documented
• fully tested
• no ongoing breaking change discussion
• 1.0.0-rc.1
• wait 1 month
• 1.0.0 (stabilization)

[iuioiua]

Note: We are making an exception of stabilizing @std/http even though a dependency, @std/net, is not yet stable.

[kt3k]

file-server apparently has low coverage number. That is because we currently can't get the coverage data of CLI entrypoint. That can be improved when Deno supports denoland/deno#23961