MLIBZ-2332: Add support for Instance ID

[thomasconner]

Description

Allow a user to provide aninstanceId config option to init() that will setup up the Kinvey API and MIC urls correctly.

const client = init({
  appKey: '<appKey>',
  appSecret: '<appSecret>',
  instanceId: '<my-subdomain>'
});
client.apiHostname // https://<my-subdomain>-baas.kinvey.com
client.micHostname // https://<my-subdomain>-auth.kinvey.com

Changes

• Support config option instanceId in client.js constructor.

Tests

• Added a test to client.spec.ts that checks if an error is thrown if instanceId is anything but a string
• Added a test to client.spec.ts that checks if an instanceId is provided that the apiHostname and micHostname are correct.

[tejasranade]

As part of this ticket, the micHostname and apiHostname config options should be marked deprecated in the API reference. Also, the instanceId option should be documented in the API reference.

[thomasconner]

I already did this. Take a look at the documentation comments above the function.

[tejasranade]

My mistake, I see it now. Can you make the following change?
"Deprecated: Host name used for Kinvey API requests": add the following - "Use the instanceID property instead"

LGTM overall.

[tejasranade]

LGTM