[MM-17251] Change to using ‘postMessage’ for desktop presence detection

[deanwhillier]

Summary

As a result of a security update to the Desktop app (context isolation), the Desktop <-> Webapp communication for presence detection broke. This PR changes the communication mechanism to use postMessage in order to get Desktop <-> Webapp communication working again.

Issue link

https://mattermost.atlassian.net/browse/MM-17251

Related Pull Requests

Webapp: mattermost/mattermost-webapp#3548

[lindalumitchell]

Are there description and test steps that can be added to the ticket for this one?

[enahum]

Basically the idea here is to have the status changing when the user is away or present, this was already done but a secfix broke this, this PR is intended to fix it back to how it was.

☝️As far as I can tell

[deanwhillier]

@lindalumitchel, the description and test steps from the original PR can be used for this one. I’ll add to the ticket as well.

[lindalumitchell]

Thanks @enahum and @deanwhillier! I tried to remove the QA label, but it looks like I don't have permission in this repo to add/remove labels, so for now can you please remove QA Review label for me, and then for future, does anyone know who I should ask to get permission in this repo to remove those labels myself?

[deanwhillier]

Added pipeline fixes from @Willyfrog, tests are now running again and passing!