gopls/internal/bug: move bug package into gopls

A follow-up change will cause it to write to
the file system.

Change-Id: I1c3b04af1d0f7b8e223d96b4bc9d1399b610f6ee
Reviewed-on: https://go-review.googlesource.com/c/tools/+/488595
gopls-CI: kokoro <noreply+kokoro@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Alan Donovan <adonovan@google.com>
diff --git a/gopls/internal/lsp/cache/snapshot.go b/gopls/internal/lsp/cache/snapshot.go
index cf2b930..c5ee812 100644
--- a/gopls/internal/lsp/cache/snapshot.go
+++ b/gopls/internal/lsp/cache/snapshot.go
@@ -29,6 +29,7 @@
 	"golang.org/x/sync/errgroup"
 	"golang.org/x/tools/go/packages"
 	"golang.org/x/tools/go/types/objectpath"
+	"golang.org/x/tools/gopls/internal/bug"
 	"golang.org/x/tools/gopls/internal/lsp/filecache"
 	"golang.org/x/tools/gopls/internal/lsp/protocol"
 	"golang.org/x/tools/gopls/internal/lsp/source"
@@ -36,7 +37,6 @@
 	"golang.org/x/tools/gopls/internal/lsp/source/typerefs"
 	"golang.org/x/tools/gopls/internal/lsp/source/xrefs"
 	"golang.org/x/tools/gopls/internal/span"
-	"golang.org/x/tools/internal/bug"
 	"golang.org/x/tools/internal/event"
 	"golang.org/x/tools/internal/event/tag"
 	"golang.org/x/tools/internal/gocommand"