`@route` starting with `?` and `:` shouldn't be joined with `/`

[timotheeguerin]

When using either at the root of the service or nested in a container we shouldn't previx those route segmeent with / as ? and : can already be considered as separators

import "@typespec/http";

using Http;

@service
namespace Contoso;

@put
@route("?pet=cat")
op a(): void;

@put
@route(":pet=cat")
op b(): void;

@route("abc")
interface Container {
  @put
  @route("?pet=cat")
  a(): void;

  @put
  @route(":pet=cat")
  b(): void;
}