DRIVERS-716 Improved Bulk Write API

[isabelatkinson]

Summary

Specifies the driver API for the new bulkWrite command. The API in the new specification was previously discussed and approved in WRITING-13533. I made a few changes to the syntax which are called out in inline comments.

An implementation in the Rust Driver of this spec is currently in review (https://github.com/mongodb/mongo-rust-driver/pull/1034). A C driver implementation is also in progress.

Test Plan

I've added unified tests in the crud directory for bulk write options, errors, and results. There are also some prose tests for bulk write batching. This seemed preferable to trying to add functionality to the unified test runner to build very large documents based on hello response values.

Basic tests are also added for the following specs:

• Transactions: executing a bulk write within a transaction
• Retryable writes: executing bulk writes with/without multi: true operations
• Stable API: appending an API version to a bulk write command

Please complete the following before merging:

• [x] Update changelog.
• [x] Make sure there are generated JSON files from the YAML test files.
• [x] Test changes in at least one language driver.
• [x] Test these changes against all server versions and topologies (including standalone, replica set, sharded clusters, and serverless).

[isabelatkinson]

(Removing spec owners as reviewers for now, going to gather initial feedback from Kevin & Jeremy)