[SPARK-27322][SQL] DataSourceV2: Select from multiple catalogs

[jzhuge]

What changes were proposed in this pull request?

Support multi-catalog in the following SELECT code paths:

• SELECT * FROM catalog.db.tbl
• TABLE catalog.db.tbl
• JOIN or UNION tables from different catalogs
• SparkSession.table("catalog.db.tbl")
• CTE relation: WITH cte AS (SELECT * FROM catalog.db.tbl) SELECT * FROM cte
• View text: CREATE VIEW view AS SELECT * FROM catalog.db.tbl; SELECT * FROM view

How was this patch tested?

New unit tests.
Existing unit tests.

[jzhuge]

This PR depends #24689 and #24686.

[SparkQA]

Test build #105820 has finished for PR 24718 at commit 70c2e68.

• This patch fails to generate documentation.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
• trait TableIdentifierHelper extends LookupCatalog
• implicit class TableIdentifierHelper(parts: Seq[String])
• case class UnresolvedRelation(table: TableIdentifierLike)
• sealed trait TableIdentifierLike
• case class CatalogTableIdentifier(catalog: TableCatalog, ident: Identifier)
• class AstBuilder(conf: SQLConf)

[jzhuge]

Close this for now since there will be changes in dependent PRs.