feat: Add messenger delegate and revoke methods (#6132)

## Explanation

The methods `delegate` and `revoke` have been added to the Messenger
class. These methods replace the need for the `RestrictedMessenger`. The
`getRestricted` method, and the `RestrictedMessenger` class, have been
removed as obsolete.

Note that the `parent` constructor parameter described in the ADR is not
implemented yet, that will come in the next PR.

## References

See this ADR PR for details: MetaMask/decisions#53
Relates to #5626

## Checklist

- [x] I've updated the test suite for new or updated code as appropriate
- [x] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [x] I've communicated my changes to consumers by [updating changelogs
for packages I've
changed](https://github.com/MetaMask/core/tree/main/docs/contributing.md#updating-changelogs),
highlighting breaking changes as necessary
- [x] I've prepared draft pull requests for clients and consumer
packages to resolve any breaking changes

---------

Co-authored-by: Elliot Winkler <elliot.winkler@gmail.com>

Author: Gudahtt

packages/messenger/CHANGELOG.md

@@ -10,11 +10,24 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Migrate `Messenger` class from `@metamask/base-controller` package ([#6127](https://github.com/MetaMask/core/pull/6127))
+- Add `delegate` and `revoke` methods ([#6132](https://github.com/MetaMask/core/pull/6132))
+  - These allow delegating or revoking capabilities (actions or events) from one `Messenger` instance to another.
+  - This allows passing capabilities through chains of messengers of arbitrary length
+  - See this ADR for details: https://github.com/MetaMask/decisions/blob/main/decisions/core/0012-messenger-delegation.md
 
 ### Changed
 
+- **BREAKING:** Add `Namespace` type parameter and required `namespace` constructor parameter ([#6132](https://github.com/MetaMask/core/pull/6132))
+  - All published events and registered actions should fall under the given namespace. Typically the namespace is the controller or service name. This is the equivalent to the `Namespace` parameter from the old `RestrictedMessenger` class.
+- **BREAKING:** The `type` property of `ActionConstraint` and `EventConstraint` is now a `NamespacedName` rather than a string ([#6132](https://github.com/MetaMask/core/pull/6132))
 - Add default for `ReturnHandler` type parameter of `SelectorEventHandler` and `SelectorFunction` ([#6262](https://github.com/MetaMask/core/pull/6262), [#6264](https://github.com/MetaMask/core/pull/6264))
 
+### Removed
+
+- **BREAKING:** Remove `RestrictedMessenger` class ([#6132](https://github.com/MetaMask/core/pull/6132))
+  - Existing `RestrictedMessenger` instances should be replaced with a `Messenger`. We can now use the same class everywhere, passing capabilities using `delegate`.
+  - See this ADR for details: https://github.com/MetaMask/decisions/blob/main/decisions/core/0012-messenger-delegation.md
+
 ### Fixed
 
 - Update `unsubscribe` type signature to support selector event handlers ([#6262](https://github.com/MetaMask/core/pull/6262))