Use `HEAD` operation for `tableExists` in REST-Catalog

[Fokko]

Feature Request / Improvement

It looks like we just load the table and fail if it raises an exception:

iceberg/api/src/main/java/org/apache/iceberg/catalog/SessionCatalog.java

Lines 180 to 187 in f2d6275

	default boolean tableExists(SessionContext context, TableIdentifier ident) {
	try {
	loadTable(context, ident);
	return true;
	} catch (NoSuchTableException e) {
	return false;
	}
	}

Instead we would love to override this for the REST-Catalog, and use the HEAD call instead:

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

Lines 833 to 864 in 97e034b

	head:
	tags:
	- Catalog API
	summary: Check if a table exists
	operationId: tableExists
	description:
	Check if a table exists within a given namespace. The response does not contain a body.
	responses:
	204:
	description: Success, no content
	400:
	$ref: '#/components/responses/BadRequestErrorResponse'
	401:
	$ref: '#/components/responses/UnauthorizedResponse'
	403:
	$ref: '#/components/responses/ForbiddenResponse'
	404:
	description:
	Not Found - NoSuchTableException, Table not found
	content:
	application/json:
	schema:
	$ref: '#/components/schemas/IcebergErrorResponse'
	examples:
	TableToLoadDoesNotExist:
	$ref: '#/components/examples/NoSuchTableError'
	419:
	$ref: '#/components/responses/AuthenticationTimeoutResponse'
	503:
	$ref: '#/components/responses/ServiceUnavailableResponse'
	5XX:
	$ref: '#/components/responses/ServerErrorResponse'

This will be more friendly on the catalog since it doesn't have to load the metadata, and will also return a faster response. We also use this when creating a view to double-check if there is not a table with the same name:

iceberg/core/src/main/java/org/apache/iceberg/rest/RESTSessionCatalog.java

Line 1303 in f2d6275

if (tableExists(context, identifier)) {

The HEAD operation will be much faster than trying to load the table.

Query engine

None

Willingness to contribute

• I can contribute this improvement/feature independently
• I would be willing to contribute this improvement/feature with guidance from the Iceberg community
• I cannot contribute this improvement/feature at this time