[11.x] Fix routeCollection get method return value when searching by dot not…

[abdel-aouby]

Changes

• Remove the use of Arr::get($this->routes, $method, []) from the get method in \Illuminate\Routing\RouteCollection::get because it allows to return a route object when searching with "dot" notation. despite the method name, parameter, and PHPDoc indicating that the search is performed by $method (e.g GET , POST ...) and should return array of Route objects when found

Changes
as described and discussed in #54541

• The current implementation of the get method in \Illuminate\Routing\RouteCollection::get has a side effect that allows us to search by "dot" notation
  example: $this->routeCollectionget->('GET.foo/index'); will return an object instance of Route (not array)
  which contradict:

1. The parameter name ($method)
2. The phpDoc that says it should return \Illuminate\Routing\Route[] and not \Illuminate\Routing\Route object as it is in this case

Solution

• Eliminate the side effect by removing the search by "dot" notation that is provided by Arr::get() and use null-coalescing operator instead to perform a search on the routes collection (first level that contains the methods)