refactor(NODE-6325): implement document sequence support

[durran]

Description

Implements OP_MSG type 1 sections for document sequences.

What is changing?

• Adds a DocumentSequence object that can be added to commands internally to leverage type 1 sections.
• Updates OpMsgRequest to properly handle document sequences in commands.
• Adds unit tests on OpMsgRequest#toBin

Is there new documentation needed for these changes?

None

What is the motivation for this change?

NODE-6325

Double check the following

• Ran npm run check:lint script
• Self-review completed using the steps outlined here
• PR title follows the correct format: type(NODE-xxxx)[!]: description
  • Example: feat(NODE-1234)!: rewriting everything in coffeescript
• Changes are covered by tests
• New TODOs have a related JIRA ticket

[nbbeeken]

Some quick win improvements.

We're calling this a feat but there's no public facing changes, maybe a refactor would be more accurate?

[nbbeeken]

LGTM