chore(NODE-6177): set up tooling for new repo

[nbbeeken]

Description

What is changing?

• Adds a new script that manages obtaining libmongocrypt and building it
• Fixes changelog

Is there new documentation needed for these changes?

No

What is the motivation for this change?

• Libmongocrypt is now versioned by the "mongodb:libmongocrypt" package spec

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

[baileympearson]

just a small comment