[Request] Prebuilt rule customization and upgrade workflows (DRAFT)

[jpdjere]

🚧 Ticket under construction 🚧
[This is a very rough draft - We need the ticket as placeholder]

Description

What: We are introducing the ability for users to customise their prebuilt rules and modifying the upgrade workflow to adapt to that change.

Background & resources

• PRs: Multiple
• Issues/metas: [Security Solution] Users can Customize Prebuilt Detection Rules: Milestone 3 kibana#174168
• Point of contact: @jpdjere @banderror
• Test environments: TBD

Which documentation set does this change impact?

ESS and serverless

ESS release

N/A

Serverless release

TBD

Feature differences

None.

API docs impact

Many changes in API, TBD

Prerequisites, privileges, feature flags

• Feature flag: prebuiltRulesCustomizationEnabled