cmd/cue: allow interspersed flags in cue cmd

All of our commands allow this as it is a default in cobra,
but we disallowed mixing flags and arguments in `cue cmd` since
the first flag was added via https://cue-review.googlesource.com/c/cue/+/4949.

There wasn't any justification to the restriction in the commit message
or code, and there aren't any tests which break when removing the line.

Moreover, `cue foo . -t tag` worked as a shortcut command before,
perhaps by accident due to how we implemented short commands,
so it doesn't make any sense for `cue cmd foo . -t tag` to now fail.

Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Change-Id: I9119e7205bf778be7d03f57fa8a22338bf3d6e5a
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1206784
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Reviewed-by: Paul Jolly <paul@myitcv.io>

cmd/cue/cmd/cmd.go

@@ -158,8 +158,6 @@ Run "cue help commands" for more details on tasks and workflow commands.
 		}),
 	}
 
-	cmd.Flags().SetInterspersed(false)
-
 	addInjectionFlags(cmd.Flags(), true, false)
 
 	return cmd

cmd/cue/cmd/testdata/script/cmd_tags.txtar

@@ -3,8 +3,8 @@ cmp stdout expect-stdout
 
 # Check that the flags can be used after any arguments;
 # such "interspersed" flags are supported by cobra by default.
-! exec cue cmd tag tags.cue tags_tool.cue -t prod -t name=bar
-stderr 'no encoding specified for file "-t"'
+exec cue cmd tag tags.cue tags_tool.cue -t prod -t name=bar
+cmp stdout expect-stdout
 
 # Verify that the new global -t flag added as a fix for issue 2510 above
 # works with the explicit or implicit "cmd" sub-command,