Add more "standard" binders

[lukaseder]

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.

[jinseopkim0]

Thank you for opening an issue. If you have a support contract with Google, please create an issue in the support console instead of filing on GitHub. This will ensure a timely response.