Enable connector templates per default

[nikku]

Proposed Changes

Implements #4455, specifically:

• Adds a way to hook up with activeTab.changed in the app
• Updates templates on switch to a Camunda 8 BPMN tab, tries every 24 hours
  • Periodic checks are needed on MacOS where the app never really stops
• enable-connector-templates=true is the default
• Change is test covered on the client
• Change is test covered on the backend (app)
• Updates what's new communication

Closes #4455
Related to camunda/camunda-docs#4187

Checklist

To ensure you provided everything we need to look at your PR:

• Brief textual description of the changes present
• Visual demo attached
• Steps to try out present, i.e. using the @bpmn-io/sr tool
• Related issue linked via Closes {LINK_TO_ISSUE} or Related to {LINK_TO_ISSUE}

[nikku]

What's new communication, v3:

[barmac]

I've tested this and it works fine. There's only one issue on MacOS which was probably introduced with the feature (not this PR). When I close the window while the templates are being fetched, there's an unhandled error in the log:

(node:47611) UnhandledPromiseRejectionWarning: TypeError: Cannot read properties of null (reading 'webContents')
    at Object.send (/Users/maciej/workspace/bpmn-io/camunda-modeler/app/lib/util/renderer.js:68:18)
    at updateConnectorTemplates (/Users/maciej/workspace/bpmn-io/camunda-modeler/app/lib/connector-templates/index.js:71:14)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
(node:47611) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 4)

It's non-critical though.

[nikku]

#4474 (comment)

Related to this I've seen the issue previously. We should be fail-safe and not fail when sending messages to non-existing main windows.

[nikku]

With 7dc67f4 we'll now log a warning to the console, and not attempt to send the message.

[barmac]

✅

[nikku]

CC @philippfromme as you worked on this previously.

[philippfromme]

Nice! 👏🏻

[philippfromme]

Good job! 💪🏻