[Stack Monitoring] Create scoped issues for "All stack monitoring server routes use iots for type-safe validation"

[jasonrhodes]

DEPENDS ON: #102436

AC:

• This issue is broken into chunks representing the work needed to do the following:
  • all SM routes use iots
  • All types used for return values are moved to common/ so that the client can refer to them too

[elasticmachine]

Pinging @elastic/logs-metrics-ui (Team:logs-metrics-ui)

[weltenwort]

The light-weight approach with io-ts that we use in the infra plugin worked out well. Here's the original demo PR that I created to pitch the convention: weltenwort#2

[smith]

Might be worth looking at @kbn/server-route-repository. @dgieselaar extracted this from APM and might have some idea about the amount of effort it would take for us to use it.

[Kerry350]

I've assigned this as it crosses over with some work I've done in #117756 so it makes most sense for me to refine this.

[Kerry350]

Closing this in favour of an AC on the route conversion issues, rather than more scoped issues: #127224 (comment)