Change wildcard qualifier type from String to TableReference

[linhr]

Which issue does this PR close?

Closes #11072.

Rationale for this change

This PR changes the wildcard qualifier type to TableReference. This avoids an implicit SQL parsing during logical planning, and makes the API more consistent.

What changes are included in this PR?

The PR changes the wildcard qualifier type for Expr::Wildcard and updates the .proto file.

Are these changes tested?

The changes are covered by existing tests.

Are there any user-facing changes?

Yes, this PR contains breaking changes to the public API.

[linhr]

Theoretically this should be a oneof, but I'm not sure if adding oneof will alter the pbjson serialization. Since we are deprecating the field anyway, I decided to handle the disambiguation in from_proto.rs and to_proto.rs instead.

Also, I'm not sure if we are allowed to make breaking changes to protobuf here. If we do, I can simply change the type of qualifier to make the code simpler.

[alamb]

Also, I'm not sure if we are allowed to make breaking changes to protobuf here. If we do, I can simply change the type of qualifier to make the code simpler.

At the moment, we don't try to maintain any backwards compatibility, thus I think we should opt for simpler code

datafusion/datafusion/proto/src/lib.rs

Lines 37 to 42 in 8aad208

	//! # Version Compatibility
	//!
	//! The serialized form are not guaranteed to be compatible across
	//! DataFusion versions. A plan serialized with one version of DataFusion
	//! may not be able to deserialized with a different version.
	//!

[alamb]

Thanks @linhr -- this change makes sense to me

I think the protobuf code could be made simpler as I mentioned, but otherwise this seems like a good cleanup to me. Thank you

[alamb]

Also, I'm not sure if we are allowed to make breaking changes to protobuf here. If we do, I can simply change the type of qualifier to make the code simpler.

At the moment, we don't try to maintain any backwards compatibility, thus I think we should opt for simpler code

datafusion/datafusion/proto/src/lib.rs

Lines 37 to 42 in 8aad208

	//! # Version Compatibility
	//!
	//! The serialized form are not guaranteed to be compatible across
	//! DataFusion versions. A plan serialized with one version of DataFusion
	//! may not be able to deserialized with a different version.
	//!

[linhr]

Thank you @alamb ! I've updated the protobuf code as suggested.

[alamb]

Thanks again @linhr