Add explicit checkbox when configuring MQTT over web sockets.

[tboman]

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Proposed changes

It appears that support for MQTT over Web Sockets was intended, as some dead code already exists. This code adds a checkbox on the MQTT configuration screen following the same pattern as for "use TLS". If unchecked, current behavior stays the same. If checked, MQTT requests use ws:// instead of mqtt:// for the run-time connection to the queue.

The workaround as it stands works, but seems a little kludgy.
https://discourse.nodered.org/t/mqtt-broken-url-and-port/1275

I am holding off on creating unit tests for MQTT node, since there is no coverage at all at this time. If people agree this is a good idea, I'll create tests for the full node.

Checklist

• I have read the contribution guidelines
• For non-bugfix PRs, I have discussed this change on the mailing list/slack team.
• I have run grunt to verify the unit tests pass
• I have added suitable unit tests to cover the new/changed functionality

[jsf-clabot]

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[coveralls]

Coverage increased (+0.05%) to 76.362% when pulling 052f1aa on tboman:topic/MQTT-over-ws into 6fa8b7f on node-red:master.

[knolleary]

Hi, the node already supports websockets.
The sidebar help for the broker config node describes how to do it. So the title of this pr confused me at first until I read the details.

So the purpose of this pr is to add an explicit checkbox, rather than just rely on the broker URL?

I can't review the code until tomorrow now, but does this maintain backward compatibility for users already using websockets with the node?

It also appears your commits have been made with a different email address to your GitHub account. As we require the contributor license agreement to be signed before accepting contributions, that relies on the commits coming from identifiable users. You'll need to fix that up before we can consider merging anything.

[tboman]

Right, the purpose is to add an explicit checkbox. Using the scheme in the broker URL works, but I've seen a lot of people trip over it when connecting to our system that required web sockets.

[tboman]

Closed, see #1881