Make webhook trigger events more specific

[mkrumrey]

Add template / parameter support to webhook trigger events.
For example it should be possible to define a callback when a specific learnerResult, defined by its id, is finished.

[abainczyk]

I suggest we implement this similar to e.g. Jira (https://developer.atlassian.com/server/jira/platform/webhooks/) and allow users to insert variables into the callback URLs. As far as I can see, the following variables would make sense:

• user.id
• project.id
• symbolGroup.id
• symbol.id
• test.id
• testReport.id
• learnerResult.id
• ltsFormula.id

What do you think about this?