Cartographer + Emitter Reimplementation

[wilyle]

Reimplements the cartographer and emitter. Changes include:

• Switch from Box<dyn Trait> to generics for pluggable components
• Use a single shared signal store rather than separate shared components between each interface combo
• Move the DigitalTwinAdapter::find_by_id call to the cartographer, thereby eliminating the need for digital twin adapters to run a separate thread
• Update the API for providers and the provider proxy to use struct-like enum variants and return Result instead of panicking
• Utilize mockall for emitter tests instead of the in-memory mock
• Prevent errors on one signal in the cartographer and emitter from taking down the entire app
• Misc minor cleanup

This partially addresses #18, but more work is needed to get provider proxies integrated

[github-actions]

Alex Recommends Report

Alex recommends the following language changes, but Alex is a regular expression based algorithm, so take them with a grain of salt.

✨ 🚀 ✨ Nothing to Report ✨ 🚀 ✨

[ashbeitz]

Please take a look at my comments. All are minor.

[ashbeitz]

Approved.