[Meta] Fleet Server Phase 1

[ruflin]

This is a meta issue about all the tasks related to Phase 1 of the Fleet Server project.

• Fleet Server is run by Elastic Agent [Elastic Agent] Embed Fleet Server as part of the Elastic Agent beats#22686 [Elastic Agent] Add the ability to run the Fleet Server beats#23736 (@blakerouse )
• Elastic Agent with Fleet Server enrolls itself Elastic Agent with Fleet Server enrolls itself #55 (@blakerouse )
• Elastic Agents can connect to Fleet Server and receive policies
• Bootstrapping of Elasticsearch indices works Bootstrapping of Elastic indices for Fleet / Fleet-Server, Phase 1 #51 (@scunningham )
• Usage of same data structure by Fleet in Kibana and Fleet Server (@nchaulet )
• Define Data model (@blakerouse )
• Actions like unenroll, upgrade etc. should work. Support the token. (@aleksmaus )
• User permission definition Define permissions user for fleet-server needs #60 (@scunningham )
• Fleet Server package fleet-server package integrations#524 (@aleksmaus )
• Fleet Server onboarding flow [Fleet] Define onboarding flow for fleet-server kibana#89396 (@mostlyjason )

CI

• Fleet-Server is built as part of the release manager (@michalpristas )
• End to end tests exists for Elastic Agent startup, agent enrollment and receiving policy. [Fleet] Infra work / new test creation, for coming Fleet Server component  e2e-testing#438 (@blakerouse )
• Scale testing setup Add scale testing for fleet-server #25 (@aleksmaus )

[ruflin]

Closing this issue as we have an e2e prototype working. All the open points I took over to Phase 2: #91