doc: write Go 1.19 release notes

[cagedmantis]

Tracking bug for writing the Go 1.19 Release Notes.

The latest state on tip can be viewed at https://tip.golang.org/doc/go1.19.

When the Go 1.19 Release Notes are complete, this should be closed, and a similar issue should be made for the next release. Previous issues are #47694, #44513, #40700, #37419, #36878, #17929, #15810, #5929, etc.

[gopherbot]

Change https://go.dev/cl/388515 mentions this issue: doc: start draft of go1.19 release notes, move go1.18 to x/website

[gopherbot]

Change https://go.dev/cl/408217 mentions this issue: doc/go1.19: update Go 1.19 relese note TODOs using relnote

[gopherbot]

Change https://go.dev/cl/408495 mentions this issue: doc/go1.19: fix strconv.Quote pkg link

[gopherbot]

Change https://go.dev/cl/408877 mentions this issue: doc/go1.19: add release notes for net/http and net/url