Client excessive routes

[RobinTail]

Address #2182 and #2183

[coveralls-official]

coverage: 100.0%. remained the same
when pulling df68e92 on client-excessive-routes
into cae198d on master.

[RobinTail]

I've got another idea...

type PathsForMethod<M extends Method> = keyof Response extends `${M} ${infer U}` ? U : never;

[RobinTail]

I'm still struggling to figure out what exactly it should be.
The original statement was that it should be Typescript error.
Meanwhile, technically it's still possible to make unlisted requests, and the response could even be typed from errorHandler.

I need to decide on the goal:

• should it be prevention of manual input mistakes
• or should it be correctness

For type error it must be another input, like OctoKit — combines method+path. I see no other neat way.
For that could introduce another variant like strict client

can be like that

// rm extends from Input and Response
// this one changes to retain original behavior
export type Provider = <M extends Method, P extends Path>(
  method: M,
  path: P,
  params: `${M} ${P}` extends keyof Input ? Input[`${M} ${P}`] : Record<string, any>,
) => Promise<`${M} ${P}` extends keyof Response ? Response[`${M} ${P}`] : any>;

// this one new:
export type StrictProvider = <K extends keyof Input>(
  request: K,
  params: Input[K]
) => Promise<Response[K]>;