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/certs/BUILD.bazel b/cluster/certs/BUILD.bazel
index ca15f0f..f16d6aa 100644
--- a/cluster/certs/BUILD.bazel
+++ b/cluster/certs/BUILD.bazel
@@ -4,15 +4,15 @@
 go_embed_data(
     name = "certs_data",
     srcs = glob(["*.crt"]),
-    package = "certs",
     flatten = True,
+    package = "certs",
 )
 
 go_library(
-    name = "go_default_library",
+    name = "certs",
     srcs = [
         ":certs_data",  # keep
     ],
-    importpath = "code.hackerspace.pl/cluster/certs",
+    importpath = "code.hackerspace.pl/hscloud/cluster/certs",  # keep
     visibility = ["//visibility:public"],
 )