feat(`cheatcodes`): create the ability to easily extend Foundry's cheatcodes using Reth's `ext` pattern

### Component

Other (please describe)

### Describe the feature you would like

From https://github.com/foundry-rs/foundry/issues/9807

Request, to extend cheatcodes: we have added a number of cheatcodes for our use-case. It would be great if we could follow the `ext` pattern found in projects such as Reth, so that we can extend the cheatcode syntax without having to fork Foundry.

### Additional context

_No response_

Start by reading the referenced Foundry issue #9807 and the Reth `ext` pattern mentioned in the request. Trace how Foundry's cheatcodes are registered and dispatched, then define what an extension point would need to support. Done means users can add cheatcodes without forking Foundry while existing cheatcode behavior remains intact.

Written by the indexing model from the issue text.