Get encoded path params

[kawmra]

What is the feature you are proposing?

Currently, with the following route, there is no way to differentiate between accessing /kv/foo/bar and /kv/foo%2Fbar:

app.get("/kv/:key{.+}", async (c) => {
  console.log(c.req.param("key")) // => Always returns "foo/bar" in both cases
})

It seems that since #659, c.req.param() now returns a decoded string by default.
But I want to distinguish whether the input parameter contained a literal / or if it was an encoded %2F.

I know that c.req.path can be used to get the raw path, but manually parsing it is cumbersome.
And if the route hierarchy (/kv) changes, the position of :key would shift, and there's no type checking to detect such changes, which is concerning.

A method like c.req.rawParam() would be useful I think.