Update toolchain to Go 1.19

[codingllama]

Update Go toolchain, allowing for a possible go.mod bump to 1.19.

Since Go 1.19 BoringCrypto is no longer a separate branch, but instead it's enabled by a GOEXPERIMENT.

Release notes: https://tip.golang.org/doc/go1.19.

[codingllama]

I think my shellcheck version is newer, but this won't hurt anyway.

[codingllama]

FIPS:

$ docker run \
  --rm=true \
  -v "$(pwd)":/go/src/github.com/gravitational/teleport \
  -v /tmp:/tmp \
  -w /go/src/github.com/gravitational/teleport \
  -h buildbox \
  -e GOMODCACHE=/tmp/gomodcache \
  -ti \
  -u $(id -u):$(id -g) \
  -e HOME=/go/src/github.com/gravitational/teleport/build.assets \
  public.ecr.aws/gravitational/teleport-buildbox-fips:teleport11 \
  /bin/bash  # stolen from `make enter`
$ go version
> go version go1.19.1 linux/amd64
$ go build ./tool/tsh
$ go version tsh
> tsh: go1.19.1 X:boringcrypto

Centos7 FIPS:

# Enter Docker as above.
$ go version
> go version go1.19.1 linux/amd64
$ go build ./tool/tsh
$ go version tsh
> tsh: go1.19.1 X:boringcrypto

[codingllama]

Comments are misleading, dronegen/windows.go seems to use make print-go-version and make print-node-version now.