feat(NODE-6342): support maxTimeMS for explain commands

[baileympearson]

Description

What is changing?

Explain commands can now have a maxTimeMS specified for them.

Corresponds to mongodb/specifications#1640. The CSOT-related changes for explain helpers will be done in https://jira.mongodb.org/browse/NODE-6375.

Is there new documentation needed for these changes?

No.

What is the motivation for this change?

Release Highlight

Explain now supports maxTimeMS

Driver CRUD commands can be explained by providing the explain option:

collection.find({}).explain('queryPlanner'); // using the fluent cursor API
collection.deleteMany({}, { explain: 'queryPlanner' }); // as an option

However, if maxTimeMS was provided, the maxTimeMS value was applied to the command to explain, and consequently the server could take more than maxTimeMS to respond.

Now, maxTimeMS can be specified as a new option for explain commands:

collection.find({}).explain({ verbosity: 'queryPlanner', maxTimeMS: 2000 }); // using the fluent cursor API
collection.deleteMany({}, { 
	explain: {
		verbosity: 'queryPlanner',
		maxTimeMS: 2000
	}
); // as an option

If a top-level maxTimeMS option is provided in addition to the explain maxTimeMS, the explain-specific maxTimeMS is applied to the explain command, and the top-level maxTimeMS is applied to the explained command:

collection.deleteMany({}, { 
	maxTimeMS: 1000,
	explain: {
		verbosity: 'queryPlanner',
		maxTimeMS: 2000
	}
);

// the actual command that gets sent to the server looks like:
{
	explain: { delete: <collection name>, ..., maxTimeMS: 1000 },
    verbosity: 'queryPlanner',
	maxTimeMS: 2000 
}

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