feat: Add config-based SRE Recipe Implementation (#826)

In this PR, we support both config-based and implementation-based SRE Recipe implementation.

- The config-based SRE Recipe makes it fast to iterate and add new SRE Recipes, as discussed in the internal design review. It also helps reduce redundant, and hacky code.
- The implementation-based SRE Recipe is kept for backward compatibility and allows for complex implementation needs that config-based SRE Recipe cannot do.
- Documentations are added for both, with support for hiding/disabling recipes.

- Migrated all existing SRE Recipe implementation to config-based YAML recipes
- Added one dummy implementation-based recipe for future reference.
- Updated sandboxctl to support running both types of recipes, using the samesandboxctl syntax right now.
- Refactored generic, reusable shell commands to a standalone utils file, instead of putting them as static methods in (conceptually irrelevant) recipe classes.

.gitignore

@@ -17,4 +17,5 @@ terraform/istio/istioctl
 terraform/istio/istio-*/**
 .token
 skaffold
-website/resources*
+website/resources*
+srerecipes.log