Fix issue #43—Callback url registered incorrectly if using route groups

[bgisme]

Attempt to fix issue #43—Callback url registered incorrectly if using route groups.

It adds an optional parameter to ServiceRegister called grouped: [PathComponent]

oAuth<OAuthProvider>(
        grouped: [PathComponent] = [],
        ...

Can be used with group routes like this...

let abComponents: [PathComponent] = ["a", "b"]
let abRoutes = routes.grouped(abComponents)
try abRoutes.oAuth(
    grouped: abComponents,
    from: Google.self,
    authenticate: "start",
    callback: "http://localhost:8080/a/b/oauth/google",
    scope: ["profile", "email"],
    redirect: "/done")
    
 // call to trigger... http://localhost:8080/a/b/start

Ungroued routes can omit the parameter. So existing usage should not change.

The parameter is passed down to FederatedServiceRouter configureRoutes(grouped:withAuthURL:authenticateCallback:on:) where the callback URL gets registered.

When breaking the callbackURL into path components, duplicate components at the head of the path are removed. So the grouped route is registered properly and matches the callback url.

Most of the work happens inside ImperialCore > Helpers > String + Tools.swift > pathComponents(grouped:)

Also added a few tests for different kinds of groups and callback urls.

Happy to add readme stuff if you like the fix.

[bgisme]

Tests for different kinds of grouped scenarios

[bgisme]

Use the new func pathComponents(grouped:) on both callbackURL and authURL

[bgisme]

Change pathComponents var to a func with grouped: [PathComponent] parameter.
Break url path into array of components like before.
Remove any duplicates with grouped at beginning of array.
Stop immediately when a component at the same index does not match.

[bgisme]

Add parameter grouped: [PathComponent]
It gets passed down in to where the callback url is parsed into path components and registered.
Any overlap between callback url path components and grouped parameter is removed before registration.
So the grouped route matches the callback url.

[0xTim]

Just an FYI I'm going to be doing an Imperial code sprint next week to go through all the issues and PRs