feat: Add --yaml-compact-seq-indent / -c flag for compact sequence indentation (#2583)

Adds a new CLI flag that enables compact sequence indentation where '- ' is
considered part of the indentation. This leverages the CompactSeqIndent()
method from the underlying go.yaml.in/yaml/v4 library.

Example output with --yaml-compact-seq-indent:
  parent:
    items:
    - one
    - two

Instead of the default:
  parent:
    items:
      - one
      - two

Closes #1841

pkg/yqlib/encoder_yaml.go

@@ -52,6 +52,9 @@ func (ye *yamlEncoder) Encode(writer io.Writer, node *CandidateNode) error {
 	var encoder = yaml.NewEncoder(destination)
 
 	encoder.SetIndent(ye.prefs.Indent)
+	if ye.prefs.CompactSequenceIndent {
+		encoder.CompactSeqIndent()
+	}
 
 	target, err := node.MarshalYAML()