[Go] Row format support for Go

### Feature Request

Implement standard Fory row format support for Go.

### Is your feature request related to a problem? Please describe

Go runtime currently lacks standard row format read/write support, which prevents full row-format interoperability with existing standard row format implementations and limits random-access row processing in Go services.

### Describe the solution you'd like

Add standard row format support in Go based on `docs/specification/row_format_spec.md`.

Scope:
- Implement row encode/decode for standard format.
- Implement standard array/map/nested-struct layout handling.
- Support null bitmap semantics, fixed 8-byte field slots, and relative offset+size for variable-width fields.
- Enforce 8-byte alignment and deterministic padding behavior.
- Add cross-language compatibility tests with Java as reference endpoint.
- Add CI coverage for Go row format tests and interoperability tests.

Out of scope:
- Compact row format.

### Describe alternatives you've considered

Using only reflection-based object serialization was considered, but it does not provide standard row format compatibility or efficient row-level random access required for cross-language row processing.

### Additional context

`docs/specification/row_format_spec.md`