refactor: re-export google proto types

The TemplatePart::Table() variant contains a google::protobuf::Empty
type which is defined in the generated_types crate.

Rather than force consumers to import two crates which have to be kept
in sync, this commit re-exports the google types within the
influxdb_iox_client crate as it's already a dependency, and makes using
types like protobuf's Duration or long-running-operation API easier for
the consumer.

influxdb_iox_client/src/client/management.rs

@@ -10,6 +10,7 @@ use std::num::NonZeroU32;
 
 /// Re-export generated_types
 pub mod generated_types {
+    pub use generated_types::google;
     pub use generated_types::influxdata::iox::management::v1::*;
 }