go: re-do the entire thing

This is a mega-change, but attempting to split this up further is
probably not worth the effort.

Summary:

1. Bump up bazel, rules_go, and others.
2. Switch to new go target naming (bye bye go_default_library)
3. Move go deps to go.mod/go.sum, use make gazelle generate from that
4. Bump up Python deps a bit

And also whatever was required to actually get things to work - loads of
small useless changes.

Tested to work on NixOS and Ubuntu 20.04:

   $ bazel build //...
   $ bazel test //...

Change-Id: I8364bdaa1406b9ae4d0385a6b607f3e7989f98a9
Reviewed-on: https://gerrit.hackerspace.pl/c/hscloud/+/1583
Reviewed-by: q3k <q3k@hackerspace.pl>
diff --git a/cluster/prodvider/hspki.go b/cluster/prodvider/hspki.go
index fabf84d..e3019c6 100644
--- a/cluster/prodvider/hspki.go
+++ b/cluster/prodvider/hspki.go
@@ -60,7 +60,7 @@
 	signerCert, _ := s.Certificate("", "")
 	req := &csr.CertificateRequest{
 		CN: principal,
-		KeyRequest: &csr.BasicKeyRequest{
+		KeyRequest: &csr.KeyRequest{
 			A: "rsa",
 			S: 4096,
 		},