REST: Reuse table metadata as part of LoadTable in serializable table

[singhpk234]

About the change

This change attempts to avoid object store call to recreate the TableMetadata from the object store in case we are making a serialized table copy of the table, this could be seen as an optimization where rather than going to the obj store we keep the serialized copy of the table metadata and then just store it and send it via wire for example (spark driver sending to executor) or can also be looked as a feature where if the catalog has redacted some sensitive info, all the serializable table respects it and reads that rather than going to the object store (which it may not have access to) for example:

• Core: TableMetadata Projection #14502

Presently its gauraded only for RESTTable and for the case when the location is null

I understand that spec wording the following:

Per REST spec the metadata location is nullable in certain cases

iceberg/open-api/rest-catalog-open-api.yaml

Lines 3396 to 3399 in 4632f31

	metadata-location:
	type: string
	description: May be null if the table is staged as part of a transaction
	nullable: true

The spec says the following but that is SHOULD and not MUST :

iceberg/open-api/rest-catalog-open-api.yaml

Line 3365 in 4632f31

The table metadata JSON is returned in the `metadata` field. The corresponding file location of table metadata should be returned in the `metadata-location` field, unless the metadata is not yet committed. For example, a create transaction may return metadata that is staged but not committed.

just wanted to float this to folks on what they think of this feature.