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/devtools/hackdoc/source/BUILD.bazel b/devtools/hackdoc/source/BUILD.bazel
index f7f09c6..cbfc4a9 100644
--- a/devtools/hackdoc/source/BUILD.bazel
+++ b/devtools/hackdoc/source/BUILD.bazel
@@ -1,7 +1,7 @@
 load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
-    name = "go_default_library",
+    name = "source",
     srcs = [
         "source.go",
         "source_depotview.go",
@@ -9,5 +9,5 @@
     ],
     importpath = "code.hackerspace.pl/hscloud/devtools/hackdoc/source",
     visibility = ["//visibility:public"],
-    deps = ["//devtools/depotview/proto:go_default_library"],
+    deps = ["//devtools/depotview/proto"],
 )