cmd/fix: allow fix to load all packages in a directory

Unlike `cue eval`, `cue fix` should load and operate on all cue files in
a directory, regardless of whether they belong to the same package or
not.

Fixes #3405

Signed-off-by: Matthew Sackman <matthew@cue.works>
Change-Id: If79c6d019b9496cfefc833d3fa5e5b6a98ae0ade
Dispatch-Trailer: {"type":"trybot","CL":1200351,"patchset":1,"ref":"refs/changes/51/1200351/1","targetBranch":"master"}

cmd/cue/cmd/fix.go

@@ -74,8 +74,9 @@ func runFixAll(cmd *Command, args []string) error {
 	}
 
 	instances := load.Instances(args, &load.Config{
-		Tests: true,
-		Tools: true,
+		Tests:   true,
+		Tools:   true,
+		Package: "*",
 	})
 
 	errs := fix.Instances(instances, opts...)

cmd/cue/cmd/testdata/script/fix.txtar

@@ -0,0 +1,17 @@
+exec cue fix ./...
+cmp good/good.cue good/good.cue.fixed
+
+-- good/good.cue --
+package good
+
+out: ["foo"] + ["bar"]
+-- good/good.cue.fixed --
+package good
+
+import list6c6973 "list"
+
+out: list6c6973.Concat([["foo"], ["bar"]])
+-- bad/bad1.cue --
+package bad1
+-- bad/bad2.cue --
+package bad2