[Alerting] [o11y] Add data collection

[chrisronline]

Relates to #98902 (comment)

Blocked: This is currently blocked until we determine which collection route we want to pursue (which is mentioned in the description below)

We need to write code that will take the necessary metrics and index them into the appropriate index. It's unclear which route we want to take here - whether we want to piggyback on existing solutions and their collection methods (such as APM or Stack Monitoring), or mimic the event_log plugin in how it creates and manages it's own index.

As part of this effort, we need to consider limitations on both sides. If we manage our own index, we need to manage all the complexity around that - resource creation, curation, security, collection interval, cloud support, data resiliency, etc. If we piggy back on an existing solution (that has theoretically solved those concerns), we might be limited on their collection strategy, such as interval or existing mappings.

[elasticmachine]

Pinging @elastic/kibana-alerting-services (Team:Alerting Services)

[chrisronline]

Closing as the new proposal is taking down a different path in the short term