[FE-2590] add client endpoint param

[ptpaterson]

Notes

Jira Ticket

The endpoint parameter is supported by other drivers. Implement it for the JS driver.

Those drivers that support endpoint do not support the scheme + domain + port parameters, so we need to determine how to handle the case where endpoint and the others are included. My suggestion is that if endpoint is set, then the other three are ignored, and that is what this PR does.

The JS driver accepts and optional argument with override options for the client.query and client.queryWithMetrics methods, but any overrides for scheme, domain, or port will not have any effect. No additional checks are required to handle query options.

Use cases

• The /linearized endpoint is not currently useable with the python driver. Or at least not reasonably. You can specify the port as 443/linearized to make it work, but it is not reasonable to advise folks to do this.
• arbitrary endpoints are not currently possible. For example if you want to send requests through a proxy. Again, you can most likely work around this by hacking the port parameter.

How to test

A test was added. No changes in environment or configuration are required to run the test.