[Go][Parquet] Support fallback encoding

[shaoting-huang]

Describe the enhancement requested

WithEncoding comments are misleading users now.

// WithEncoding defines the encoding that is used when we aren't using dictionary encoding.
//
// This is either applied if dictionary encoding is disabled, or if we fallback if the dictionary
// grew too large.
func WithEncoding(encoding Encoding) WriterProperty {
	return func(cfg *writerPropConfig) {
		if encoding == Encodings.PlainDict || encoding == Encodings.RLEDict {
			panic("parquet: can't use dictionary encoding as fallback encoding")
		}
		cfg.wr.defColumnProps.Encoding = encoding
	}
}

Currently, Go parquet fallback encoding is hardcoded as plain encoding. See fallbackToPlain. It is better to support custom fallback encoding.

Component(s)

Go, Parquet