feat: Allow services to run at startup

[crookse]

Summary

• Placed types and interfaces to be reused in interfaces.ts and types.ts
• Added runAtStartup to service interface
• Added Server.addResource().
• Refactored server to allow services to run at startup
• Removed T prefix from types. I don't know why I started doing this, but they're obviously types because they come from the types.ts file. woooooOoOopz.
• Started effort to move our server to expect a service interface as opposed to the Service class (kind of like how we're doing it for the error handler -- we expect an interface, not a class)

[ebebbington]

i think there will also be problems with #getRequest, because that method uses this, but inside deno's listen API, this will refer to the function as our server class is no longer in the scope

[ebebbington]

Docs needed for website too i assume?

[crookse]

@ebebbington , yea docs are needed