fix(plc4go/spi): preserve WithByteOrder in UpcastReaderArgs/UpcastWriterArgs

[khalidDaoud]

Summary

• UpcastReaderArgs/UpcastWriterArgs now preserve WithReaderWriterArgs concrete types instead of wrapping them in readerWriterArg

Problem

UpcastReaderArgs wraps every arg in readerWriterArg{arg, writerArg{}}. When the arg is already a WithReaderWriterArgs (e.g. codegen.WithByteOrder), this wrapping changes the concrete type from withOptionByteOrder to readerWriterArg.

FieldCommons.ExtractByteOrder does a type switch on withOptionByteOrder — which no longer matches the wrapped type. Result: ExtractByteOrder returns nil, and SwitchParseByteOrderIfNecessary skips the byte order switch entirely.

This means codegen.WithByteOrder(binary.LittleEndian) passed to ReadSimpleField/WriteSimpleField is silently ignored — fields are read/written with the buffer's default byte order.

Fix

Check if the arg already implements WithReaderWriterArgs before wrapping:

if rw, ok := arg.(WithReaderWriterArgs); ok {
    result[i] = rw
} else {
    result[i] = readerWriterArg{arg, writerArg{}}
}

Affected protocols

All protocols using byteOrder='LITTLE_ENDIAN' at the type level in mspec: ADS, AB-ETH, OPC UA, IEC 60870-5-104.

Test plan

• All existing S7 parser/serializer tests pass (no regressions)
• IEC 60870-5-104 parser/serializer tests pass (65/65 with both this fix and the getLengthInBits template fix from fix(go-codegen): chain getLengthInBits for middle-tier discriminated types #2493)