Add Regex sub route helper function which passes arguments similar to routef

[polomani]

Is your feature request related to a problem? Please describe.
There are cases when I would like to not treat / as a sub-routing symbol.
This can be useful for instance in OData functions. Those functions are parts of request path, not a query and hence will not be url-encoded by an http client:

{{my-cool-odata-api}}/Calculate(Expression='1/2 + PI()')

The slash in this expression will not allow me to use routef with /Calculate(%s), since / is a sub-routing separator, so it'll just split my function into 2 pieces.

Describe the solution you'd like
An extra sub route helper, which works similar to routef but uses Regex:

/// **Description**
///
/// Filters an incoming HTTP request based on the request path using Regex (case sensitive).
///
/// If the route matches the incoming HTTP request then the Regex groups will be passed into the supplied `routeHandler`.
/// This is similar to routex but also allows to use matched strings as parameters for a controller.
/// 
/// **Parameters**
///
/// `path`: Regex path.
/// `routeHandler`: A function which accepts a seq<string> of the matched groups and returns a `HttpHandler` function which will subsequently deal with the request.
///
///
let routexp (path : string) (routeHandler : seq<string> -> HttpHandler): HttpHandler =
    let pattern = sprintf "^%s$" path
    let regex   = Regex(pattern, RegexOptions.Compiled)

    fun (next : HttpFunc) (ctx : Microsoft.AspNetCore.Http.HttpContext) ->
        let result  = regex.Match (SubRouting.getNextPartOfPath ctx)
        match result.Success with
        | true  -> 
            let args = result.Groups |> Seq.map (fun x -> x.Value)
            routeHandler args next ctx 
        | false -> skipPipeline