Backport of Add generic experiments configuration and use it to enable catalog v2 resources into release/1.16.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #17604 to be assessed for backporting due to the inclusion of the label backport/1.16.

The below text is copied from the body of the original PR.

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Description

We wanted the next gen catalog as resources feature to be disabled by default for now with the option to enable it. I could have added another boolean flag to enable like we have done for some other features but instead decided to rip off of vault and add an experiments config setting.

The advantages of this approach are:

1. We don't have to keep adding one-off config changes every time we want to introduce an experimental feature.
2. For features that will eventually be always on, we don't want to maintain the one-off booleans. Using a string slice allows us to simply ignore older names.

Testing & Reproduction steps

• Dev Server - this enables the catalog-resources experiment by default
• Non-Dev Server - this will have the catalog resources disabled by default
• Non-Dev Server + experiments = ["catalog-resources"] - this enables the experiment

PR Checklist

• updated test coverage
• external facing docs updated
• appropriate backport labels added
• not a security concern

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Overview of commits

• ad6652a - 7a1e99b

[github-team-consul-core-pr-approver]

Auto approved Consul Bot automated PR