[@sentry/tracing] Express route tracing

[xr0master]

Should add the ability to track express routes. What methods to track is set through options.
By default, methods are ignored.

Example:

integrations: [// enable HTTP calls tracingnewSentry.Integrations.Http({tracing: true}),// enable Express.js middleware tracingnewTracing.Integrations.Express({ app,methods: ['get','post']}),],tracesSampleRate: 1.0,

This PR is relevant to: #2968

[kamilogorek]

Thanks for the PR, looks good! However, I think it should be possible to reuse the very same function for all possible router methods.

[xr0master]

the use function is not a router method, so I hesitated to add it or not... I left it aside.
But I agree that it is possible to rewrite the code a bit to use the same logic.

[xr0master]

With a new commit, the same logic was used.
use method has remained on the sidelines for now, it's easier to separate it from route methods. But if there is a goal to reduce the size, then we can use one function and inject the use method in the constructor.

[xr0master]

Or use can work exactly like a route method, but then there is a chance that developers will forget to add this method or methods and Performance will be empty. But may be nothing wrong here.

[kamilogorek]

Thanks! :)