feat(typescript): type improvements

[chimurai]

Description

Improve TypeScript typings.

• Removed @types/express peerDependency
• Contextual Typing support for express-like servers

Motivation and Context

• fixes fix(types): make request & response generic and remove express dependency #478
• fixes Move @types/express to dependencies #683
• fixes Type regression (express.Request -> http.IncomingMessage) #692
• fixes Breaking change in 2.0.1 #650
• fixes chore(typescript): extract handlers types #603
• fixes ResponseInterceptor recipe types mismatch #632
• fixes Expose HTTP Proxy middleware, so it can be used outside express #687
• fixes fix(types): fix type regression #700
• fixes responseInterceptor uses more constrained types than onProxyRes provides #708
• fixes TypeScript regression in 2.0.3 #713
• fixes Handler types are incorrectly coupled to express.js #719
• fixes Improve Type support #720
• fixes refactor: use base node http types #721
• fixes refactor: use base node http types #723

How has this been tested?

• tests
• CI

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[coveralls]

Coverage: 97.872%. Remained the same when pulling 6c7d2c4 on type-improvements into fd4e558 on master.