Remove unused parser resource plumbing

internal/commandmeta/metadata.go

@@ -2,11 +2,6 @@
 // its command-line backend.
 package commandmeta
 
-import (
-	"context"
-	"io"
-)
-
 // Key identifies one command inside one routing snapshot.
 type Key uint64
 
@@ -181,14 +176,10 @@ type Result struct {
 	Failure         *Failure
 }
 
-// ParseOptions makes parser context and streams explicit.
+// ParseOptions selects flag aliases for parser contexts.
 type ParseOptions struct {
 	// FlagAliasesForPath selects aliases for the actual parser context when
 	// routing has not already selected one. It overrides FlagAliases when set.
 	FlagAliasesForPath func([]string) []FlagAlias
-	Context            context.Context
-	In                 io.Reader
-	Out                io.Writer
-	Err                io.Writer
 	FlagAliases        []FlagAlias
 }