fix(NODE-5213): ChangeStream.tryNext() should return TChange type

[alecgibson]

Description

What is changing?

Update ChangeStream.tryNext() return type to be consistent with ChangeStream.next().

The underlying AbstractCursor has the same return type for both.

Is there new documentation needed for these changes?

If these API docs aren't auto-generated, then yes.

What is the motivation for this change?

Avoiding having to cast when using ChangeStream.tryNext().

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

[alecgibson]

I didn't know if tests were needed for type changes; I'm assuming making a type stricter, and it still building is good enough...?

[nbbeeken]

Thank you for the improvement @alecgibson! Changing TS types to something more strict is always a little gray but reflecting the TChange return type is certainly more correct and useful, so we're happy to pull it in for the next release. I just threw in some quick tests to make sure our three methods for receiving changes stay the same.

Edit: The PR title changes are so we can call attention to it in the release notes