Downstream changes: drivers should sync BSON corpus spec tests with mongodb/specifications@ff5d91f. Specifically:

• There are new decodeErrors tests for document.json, regex.json, and top.json
• There are new parseErrors tests for top.json
• There are new prose tests for encoding BSON documents and regex types.

Existing language in the spec was also relaxed to no longer require drivers to successfully parse parseErrors tests in binary.json and top.json with a non-Extended JSON parser (to check for general JSON syntax errors). Also, an allowance was made for drivers that parse Extended JSON directly into language types (with regard to evaluating parseErrors).

Per DRIVERS-101, drivers are expected to validate that C strings do not contain embedded null bytes.

We should add spec or prose tests to verify BSON C strings with embedded null bytes are rejected when serialized.