Add experiment promotion banner for security policies

What does this MR do and why?

This MR adds experiment promotion banner

New banner for experimental features promotions is added and can be permanently dismissed

There is a link to feedback issue

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

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Image	Description
	Before
	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

Enable feature flags

Feature.enable(:security_policies_policy_scope)

Feature.enable(:compliance_pipeline_in_policies)

1. Go to a Group -> Secure -> Policies
2. See banner on top
3. Try all links and banner, make sure it leads both to docs and feedback issue
4. Dismiss banner, refresh page, make sure banner is no longer visible
5. Remove key security_policies_experimental_features from local storage and make sure banner is visible again

Related to #438708 (closed)