v1: database (CXX-3237, CXX-3238)

[eramongodb]

Resolves CXX-3237 and CXX-3238 for the v1::database component and implements dependent functions in v1::client.

Similar to prior PRs, some parameter types are updated for better consistency with their ownership semantics. An incorrect const qualifier on .has_collection() inherited from v_noabi is also removed.

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The most notable difference between the former v_noabi implementation and the new v1 implementation is that the std::string name; internal data member is removed in favor of calling mongoc_database_get_name(). This change requires updating some v_noabi mocked database tests to satisfy the expected call to .name() (both explicitly and internally) when the database object may not be backed by an actual mongoc_database_t object (_impl == nullptr). However, this behavior should not be observable to public API users of v_noabi::database.

Another notable change is that the v1 implementation of .has_collection() checks for error.code != 0 rather than the v_noabi implemention which checks error.domain != 0. Although I do not expect this makes any practical difference given the behavior of the mongoc library, it is a notable change consistent with the general improvements by v1 API to mongocxx's error handling behavior w.r.t. error codes and error categories.

Lastly, similar to what was done for client::watch(), the v1 implementation of database::watch() avoids the need to create an intermediate BSON document of the form {"pipeline": [...]} in favor of simply passing [...] directly and allowing mongoc to create the pipeline field instead. However, the v_noabi implementation continues to create the "pipeline" field manually for backward compatibility with existing v_noabi mocked tests. Although this is not strictly necessary as it is internally-observable-only behavior, it nevertheless keeps the changes to v_noabi test code minimal to help validate backward compatibility of the v_noabi refactor. Where permitted, the v1 implementation also tries to pass nullptr as argument for optional parameters to avoid redundant work parsing empty bson_t documents.

[kevinAlbs]

LGTM with minor test suggestions and possible further reuse.

[kevinAlbs]

Minor: but I expect the if (ptr) is not needed.

[kevinAlbs]

Suggested change

	set_client_error(error);
	set_server_error(error);

Minor test discrepancy. I expect this is still thrown as a server error because the reply has a "code" field.

[eramongodb]

Good catch. Updated as suggested.