feat: namespace routing

[Totodore]

Motivation

Adding Namespace routing would allow to add a layer of multiplexing and also match the features of the official socket.io client.

Close issue #212.

Solution

Because I think that a regex based solution is way to slow and overkill for a simple router feature, the routing is implemented using the matchit crate. This allow to have a simple syntax for path parameters: /admin/{id}/board and even wildcards /admin/{*path}.
One of the main drawbacks is the need of an adjacent buffer to store namespace because it is not possible to iterate over the path /values of the router. So currently this is using the slab crate from tokio to store namespace and the router only stores indexes.

Performance

Here are some benchmark results to compare previous Hashmap based implementation with the new based on Router + Slab:

Todo

• Provide an extractor for the connect handler to get path parameters
• Update tests and examples
• Update documentation

[Totodore]

After multiple experimentations and attempts to solve this problem I decided to report the following features for future PRs:

• The extraction of parameters. Only the namespace path will be extracted.
• The usage of dynamic namespace with broadcast operators. Meaning that it won't be possible to select a dynamic namespace with the io.of(...) operator.