fix(NODE-4977): load snappy lazily

[nbbeeken]

Description

What is changing?

• added getSnappy
• use it in the compression path so its imported lazily
• added a test to assert a small hardcoded list of deps upon importing the driver
• added a test that launches a new node process to test lazy importing
  • wrote a utility to structure this like a mocha test

Is there new documentation needed for these changes?

Perhaps, when we've completed the related investigations we should capture out approach to optional importing and how it can effect bundling.

What is the motivation for this change?

We only want to import an optional dependency if our library is actually using it. Snappy may be present for other reasons, and node's dependency resolution doesn't differentiate if an optional peer installed is for "our" need or for coincidentally another sibling package.

Release Highlight

Snappy loaded lazily

Unlike our other compression mechanisms snappy was loaded at the module level, meaning it would be optionally imported whether or not the driver was configured to use snappy compression. Snappy is now aligned with our other optional peer dependencies and is only loaded when enabled.

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

[addaleax]

@nbbeeken I don’t think I have the time for a full review right now :)