Allow other modules to modify vitals response via hooks.

Problem/Motivation

Currently Vitals does not allow modules to modify the response that will be sent when viewing the /vitals/{token} url.

Consider the following example:

• The vitals endpoint for a site is monitored and an alert is raised if any modules show pending security updates.
• A security release was recently issued for a module.
• Due to the complexity of the update, the security release cannot be applied quickly. However, a patch has been added to resolve the security vulnerability.

In this scenario, there is no simple way to prevent the patched module from appearing in the vitals reponse. A developer could technically create their own VitalsCheck plugin to override the "updates" VitalsCheck plugin, but it would be much easier if the VitalsCheck plugins could instead allow other modules a chance to alter their response.

Steps to reproduce

N/A

Proposed resolution

My current thought is to have a $this->moduleHandler->alter('my_custom_data', $my_data); in some sort of base VitalsCheck class.

I may also consider a second alter hook for the complete vitals response before it is sent. That could potentially be useful to add in some extra data without needing to implement a complete VitalsCheck plugin.

Remaining tasks

• Plan the implementation
• Implementation
• Documentation
• Add tests

User interface changes

N/A

API changes

I don't think there will be any official API changes, but will update this section if that changes.

Data model changes

N/A