Allow OOTB stack monitoring rules to be edited and created from Rules and Connectors page

[ravikesarwani]

Currently (7.11) the users cannot edit stack monitoring default (out-of-the-box) rules from the Rules and Connectors page. To review and modify all available rules, the users need to use Enter setup mode on the Cluster overview page in Stack Monitoring.
This issue enables viewing, editing and creating additional stack monitoring rules from the Rules and Connectors page, just like all the other rule types.

Why
We want this feature for the following reasons:

1. Consistent user experience and central place for users to manage all the rules including stack monitoring OOTB rules
2. Enables use cases like this: Say user wants to alert when CPU is 75% for last 5 minutes and send an email. When its 85% for last 10 minutes they want to send a pagerduty alert. Allowing creation can enable these use cases.

Testing scenario
We should test to make sure that we can give a workable experience on creation and alert visualization.

1. Creation flow shows clearly that they are creating stack monitoring rules.
2. Visualization of the rules & alert in SM UI works for the following kind of scenario:

• There is a default CPU usage rule.
• User creates another rule of the type called "CPU Usage Pagerduty" where he has configured the alert to fire when CPU Usage is 95% for the last 5 min (average) and sends a pagerduty alert.
  In this scenario both alerts would be visible in the UI. User can visualize them without error.

[elasticmachine]

Pinging @elastic/stack-monitoring (Team:Monitoring)

[jasonrhodes]

Big +1 on this from me, I think we should aim to make our alerts as consistent as we can with the others, even where we are providing some out of the box convenience to auto-create them for people.

[ravikesarwani]

I am reopening this issue as I don't think we fixed this. The last I understand was that we have more research to do to make this work and the temporary change was reverted back.