Decouple Secret Detection rules from scanning logic
## Overview
TODO: @amarpatel fill this out
## Problem to solve
TODO: @amarpatel fill this out
## Definition of done
- Establish a SSoT for GitLab-maintained Secret Detection rules
- Update all existing projects to use this new centralized ruleset
- Document how to update existing rules or create new ones in this repo
- Develop a process to update internal projects to use new versioned rulesets
At the end of each phase...
1. :white_check_mark: Phase 1: The new secret detection rules repository will be established.
2. :white_check_mark: Phase 2: After Phase 2.1, the secrets analyzer will be using it as the SSOT. After Phase 2.2, the secret push protection gem and the secret detection service (SDS) wil be using it as the SSOT.
3. Phase 3: Remaining GitLab projects that detect secrets will use it as the SSOT.
4. ~~Phase 4: The initial improvements that have been identified will have been made. This phase is much more fluid than the previous phases, meaning the order the improvements in this phase are made can vary, the improvements can largely be made independently, and other new improvements may be added to this phase. This phase could also potentially be moved to a separate epic as we get further along with this epic.~~ Phase 4 items have either been closed or moved to https://gitlab.com/groups/gitlab-org/-/epics/14009+s
Phase 1 and 2 should be done linearly and in order. Phase 3 and 4 can be done in any order as well as simultaneously.
## Proposal ([**Epic Dashboard**](https://epic-dashboard-gitlab-org-tenant-scale-group-4aecf10d1d02154641.gitlab.io/epic_14534))
* Phase 1 - Setup new rules repo
* https://gitlab.com/gitlab-org/gitlab/-/issues/478289+s
* https://gitlab.com/gitlab-org/gitlab/-/issues/478288+s
* https://gitlab.com/gitlab-org/gitlab/-/issues/478287+s
* https://gitlab.com/gitlab-org/gitlab/-/issues/472852+s
* https://gitlab.com/gitlab-org/gitlab/-/issues/478285+s
* Phase 2 - Switch SD team projects over to use it
* 2.1 Switch secrets analyzer to use it
* https://gitlab.com/gitlab-org/gitlab/-/issues/478283+s
* https://gitlab.com/gitlab-org/gitlab/-/issues/478284+s
* 2.2 Switch SPP gem and SDS over to use it
* https://gitlab.com/gitlab-org/gitlab/-/issues/478282+s
* https://gitlab.com/gitlab-org/gitlab/-/issues/478281+s
* Phase 3 - Switch other projects over to use it
* https://gitlab.com/gitlab-org/gitlab/-/issues/415690+s
* https://gitlab.com/gitlab-org/gitlab/-/issues/498580+s
* https://gitlab.com/gitlab-org/gitlab/-/issues/498582+s
* https://gitlab.com/gitlab-org/gitlab/-/issues/488395+s
* https://gitlab.com/gitlab-org/gitlab/-/issues/506700+s
* https://gitlab.com/gitlab-org/gitlab/-/issues/506701+s
* Phase 4 - Improve rules repo
Phase 4 items have either been closed or moved to https://gitlab.com/groups/gitlab-org/-/epics/14009+s
epic