refactor!: improve router

[pi0]

This a followup PR on #809 to improve router interface.

The internal code had been rewritten to leverage a much cleaner class pattern and rou3 was upgraded to v0.2.x with a new (method, path) signature.

Router public changes (#787):

• router.use(path, handler) is deprecated. Use router.all(path, handler) instead.
• (!!) router.add(path, method: Method | Method[] signature is changed to `router.add(method: Method, path)
• app.resolve and handler.__resolve signature changes from (path) to (method, path).
• Router resolver allows resolving params as well (wanted feature for websocket users)

Type changes:

• RouteNode type is changed to RouterEntry
• While router.add allows lowercase methods, we prefer upper-case (consistent with web Request normalization) in internal types (HTTPMethod)
• CreateRouterOptions type is renamed to RouterOptions