In `SerializedMessage{,Backward}Writer`, rename `WriteSerializedMessage()`
to an overload of `WriteString()`.
Exclude message objects from the regular stringifying `WriteString()` because
they are stringified in the text format, which is rarely intended as a field
value. A separate overload serializes a message object in the binary format.
PiperOrigin-RevId: 885216863
Riegeli/records is a file format for storing a sequence of string records, typically serialized protocol buffers. It supports dense compression, fast decoding, seeking, detection and optional skipping of data corruption, filtering of proto message fields for even faster decoding, and parallel encoding.
See documentation.
Riegeli file format will only change in a backward compatible way (i.e. future readers will understand current files, but current readers might not understand files using future features).
Riegeli C++ API might change in incompatible ways.