feat: make DefaultLogicalExtensionCodec support serialisation of buil… (#20638)

## Which issue does this PR close?

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- Closes #16944.

## Rationale for this change

Currently, the `LogicalExtensionCodec` implementation for
`DefaultLogicalExtensionCodec` leaves `try_decode_file_format` /
`try_encode_file_format` unimplemented (returning "not implemented"
errors). However, the actual serialization logic for built-in file
formats — arrow, parquet, csv, and json— already exists in their
respective codec implementations. All we need to do is tag which format
is being used, and delegate to the corresponding format-specific codec
to handle the data.
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## What changes are included in this PR?

Added a `FileFormatKind` enum and a `FileFormatProto` message to
`datafusion.proto` to identify the file format type during transmission.
Implemented `try_decode_file_format` and `try_encode_file_format` for
`DefaultLogicalExtensionCodec`, which dispatch
serialization/deserialization to the corresponding format-specific codec
based on the format kind. Note that Avro is not covered because the
upstream repository has not yet implemented the corresponding Avro
codec, so Avro support is not functional at this time.

## Are these changes tested?

Yes. Roundtrip tests are included for csv, json, parquet, and arrow. 

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## Are there any user-facing changes?

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Author: Acfboy

datafusion/proto/proto/datafusion.proto

@@ -270,6 +270,25 @@ message CopyToNode {
   repeated string partition_by = 7;
 }
 
+// Identifies a built-in file format supported by DataFusion.
+// Used by DefaultLogicalExtensionCodec to serialize/deserialize
+// FileFormatFactory instances (e.g. in CopyTo plans).
+enum FileFormatKind {
+  FILE_FORMAT_KIND_UNSPECIFIED = 0;
+  FILE_FORMAT_KIND_CSV = 1;
+  FILE_FORMAT_KIND_JSON = 2;
+  FILE_FORMAT_KIND_PARQUET = 3;
+  FILE_FORMAT_KIND_ARROW = 4;
+  FILE_FORMAT_KIND_AVRO = 5;
+}
+
+// Wraps a serialized FileFormatFactory with its format kind tag,
+// so the decoder can dispatch to the correct format-specific codec.
+message FileFormatProto {
+  FileFormatKind kind = 1;
+  bytes encoded_file_format = 2;
+}
+
 message DmlNode{
    enum Type {
     UPDATE = 0;