feat: improve mongo support

[mhdawson]

• build url needed to connect
• move auth info to the right nesting
• add test for case when port is used

Signed-off-by: Michael Dawson mdawson@devrus.com

[mhdawson]

@tchughesiv could you test this out. It should be used as:

let bindings;
try {
    // check if the deployment has been bound to a pg instance through
    // service bindings. If so use that connect info
    bindings = serviceBindings.getBinding('MONGODB', 'mongodb');
} catch (err) { // proper error handling here
};

const url = bindings.url + '/' + database + '?retryWrites=true&w=majority';
const client = new MongoClient(url, bindings.connectionOptions);

passing the connectionOptions to new MongoClient() will allow additional connections to be set through service bindings if/when they are supported/provided.

Note that I did move the username/password to the structure I found in options under new MongoClient in - https://mongodb.github.io/node-mongodb-native/3.4/api/MongoClient.html

This is technically breaking but since we are at a 0. version and nobody should be depending on this yet that is the best thing to do.

Once we confirm this works, we'll also have to fix up the Typscript .d.ts file to reflect that what is returned is not just a connectionOptions object.

[tchughesiv]

@mhdawson database is not a requirement to connect to cluster

const url = bindings.url + '?retryWrites=true&w=majority';

or just

const client = new MongoClient(bindings.url, bindings.connectionOptions);

[mhdawson]

@tchughesiv in terms of the database great if we don't need to add, ideally we could just pass in the results of what we get back from the bindings after having set any additional options needed on the bindings.connectionOptions object.

[mhdawson]

@tchughesiv confirmed this PR works for him, landing.