Add more "standard" binders

The readme mentions the following binder support:

- `BYTES` -> `java.nio.ByteBuffer` (this doesn't actually seem to be supported. Only `com.google.cloud.ByteArray` is supported, it seems from code in `com.google.cloud.spanner.r2dbc.v2.ClientLibraryBinder`)
- `DATE` -> `com.google.cloud.Date`
- `JSON` -> `com.google.cloud.spanner.r2dbc.v2.JsonWrapper`
- `TIMESTAMP` -> `com.google.cloud.Timestamp`

See:

- https://github.com/GoogleCloudPlatform/cloud-spanner-r2dbc?tab=readme-ov-file#mapping-of-data-types

It is inconvenient for client libraries (especially third parties) to have dependencies on cloud-spanner-r2dbc or cloud-core data types. It would be better, in my opinion, to support:

- `LocalDate` as an equivalent of `com.google.cloud.Date`
- `Instant` or `OffsetDateTime` as an equivalent of `com.google.cloud.Timestamp`
- `String` as an alternative for `JsonWrapper`

At the same time, I wonder if more array types could be supported, e.g. `Long[]` or `Integer[]`. `long[]` doesn't support null elements.