Add support for SurrealDB v3 structured error handling

[mumoshu]

Introduce ServerError for SurrealDB v3 structured errors while preserving backward compatibility with the existing RPCError and QueryError types.

Keep using RPCError in SurrealDB v2 (although we recommend upgrading to v3, and' RPCError' has been deprecated to signal that).

Use ServerError on SurrealDB v3.

Errors embedded inside QueryResult remain as QueryError.

_, err := surrealdb.Select[map[string]any](context.Background(), db,
	models.Table("nonexistent_table_for_test"),
)

// Use it on SurrealDB v3 only
var se surrealdb.ServerError
if errors.As(err, &se) {
	// Get access to new error fields like Kind, Details, and Cause
}

// You can also use this idiom to obtain the cause
var cause surrealdb.ServerError
if errors.As(errors.Unwrap(se), &cause) {
	// Get access Kind, Details, and Cause of Cause
}

Based on #380

[mumoshu]

Thanks for your contribution, @kearfy!