refactor(NODE-5912): make server.command an async function

[W-A-James]

Description

What is changing?

• Server.command is now written with explicit async/await syntax
• Removed Server.commandAsync and replaced all references
• Removed ConnectionPool.withConnection, ConnectionPool.withReauthentiation
• Refactored ConnectionPool.reauthenticate to use explicit async/await syntax and exported it for internal use in Server.command
• Refactored ConnectionPool.checkOut to use async/await syntax with the support of promiseWithResolvers helper function
• Removed callback property from WaitQueueMember and replaced it with explicit reject and resolve properties for more ergonomic use with promiseWithResolvers in ConnectionPool.checkOut

What is the motivation for this change?

NODE-5912, NODE-5913

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

[W-A-James]

Currently only consistently failing these two tests across load-balanced variants. It seems strange to me that we'd fail operation count tests, but not connection pinning tests.

[alenakhineika]

A couple of housekeeping questions:

• Does this PR also cover NODE-5913? If so to not forget to close that ticket as well and maybe mention its number in the current PR.
• Double-check the list in the PR description to see if it meets all expectations.

[baileympearson]

pending CI, LGTM

[alenakhineika]

CI fails because the AWS Secrets Secrets Manager is not implemented yet NODE-5507 and Serverless credentials are rotated (should be fixed soon).