all: Become a Go module (fixes #5148) (#5384)

* go mod init; rm -rf vendor

* tweak proto files and generation

* go mod vendor

* clean up build.go

* protobuf literals in tests

* downgrade gogo/protobuf

vendor/github.com/gobwas/glob/.gitignore

@@ -0,0 +1,8 @@
+glob.iml
+.idea
+*.cpu
+*.mem
+*.test
+*.dot
+*.png
+*.svg