chore!: Introduce ZITADEL v3 (#9645)

This PR summarizes multiple changes specifically only available with
ZITADEL v3:

- feat: Web Keys management
(https://github.com/zitadel/zitadel/pull/9526)
- fix(cmd): ensure proper working of mirror
(https://github.com/zitadel/zitadel/pull/9509)
- feat(Authz): system user support for permission check v2
(https://github.com/zitadel/zitadel/pull/9640)
- chore(license): change from Apache to AGPL
(https://github.com/zitadel/zitadel/pull/9597)
- feat(console): list v2 sessions
(https://github.com/zitadel/zitadel/pull/9539)
- fix(console): add loginV2 feature flag
(https://github.com/zitadel/zitadel/pull/9682)
- fix(feature flags): allow reading "own" flags
(https://github.com/zitadel/zitadel/pull/9649)
- feat(console): add Actions V2 UI
(https://github.com/zitadel/zitadel/pull/9591)

BREAKING CHANGE
- feat(webkey): migrate to v2beta API
(https://github.com/zitadel/zitadel/pull/9445)
- chore!: remove CockroachDB Support
(https://github.com/zitadel/zitadel/pull/9444)
- feat(actions): migrate to v2beta API
(https://github.com/zitadel/zitadel/pull/9489)

---------

Co-authored-by: Livio Spring <livio.a@gmail.com>
Co-authored-by: Stefan Benz <46600784+stebenz@users.noreply.github.com>
Co-authored-by: Silvan <27845747+adlerhurst@users.noreply.github.com>
Co-authored-by: Ramon <mail@conblem.me>
Co-authored-by: Elio Bischof <elio@zitadel.com>
Co-authored-by: Kenta Yamaguchi <56732734+KEY60228@users.noreply.github.com>
Co-authored-by: Harsha Reddy <harsha.reddy@klaviyo.com>
Co-authored-by: Livio Spring <livio@zitadel.com>
Co-authored-by: Max Peintner <max@caos.ch>
Co-authored-by: Iraq <66622793+kkrime@users.noreply.github.com>
Co-authored-by: Florian Forster <florian@zitadel.com>
Co-authored-by: Tim Möhlmann <tim+github@zitadel.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Max Peintner <peintnerm@gmail.com>

.github/pull_request_template.md

@@ -1,3 +1,8 @@
+<!--
+Please inform yourself about the contribution guidelines on submitting a PR here: https://github.com/zitadel/zitadel/blob/main/CONTRIBUTING.md#submit-a-pull-request-pr. Take note of how PR/commit titles should be written and replace the template texts in the sections below. Don't remove any of the sections. It is important that the commit history clearly shows what is changed and why.
+Important: By submitting a contribution you agree to the terms from our Licensing Policy as described here: https://github.com/zitadel/zitadel/blob/main/LICENSING.md#community-contributions.
+-->
+
 # Which Problems Are Solved
 
 Replace this example text with a concise list of problems that this PR solves.