Accept OptionallyQualifiedName in TableEditor::setName()

[morozov]

Background

TableEditor was the first object editor introduced (#6660). Later, it was followed by UniqueConstraintEditor (#6685) and ForeignKeyConstraintEditor (#6728).

The API of TableEditor was designed to closely mimic the Table constructor. Specifically, setName() accepts string. The other two were designed to provide an upgrade path to 5.0 where we eventually want to express object names as Name instances.

In order to unify the API of the editors and avoid an unnecessary BC break in the future, I want TableEditor#setName() to also accept a Name.

Implementation details

In order to accommodate this API change, we need to revert the introduction of the usage of TableEditor in all existing code, because a Table in 4.x is not guaranteed to have a valid (in terms of the SQL syntax) name. During the merge up, all those reverts will be discarded, so the 5.0.x code will keep using the editor.

Additionally, I'm unmarking the Table constructor as @internal for now. Unlike the UniqueConstraint and ForeignKeyConstraint editors, the existing Table editor hasn't fully replaced the usage of the constructor in 5.0, so expecting the end users to be able to not use the constructor is unrealistic. In its current state, it will lead to a worse user experience.