Create basic url handler

[elYanuki]

We really only need this right now for the rent confirmation but later in the project we need this system anyways because it makes the usability better when you can share a link to the thing your actually doing not just the homepage so its smart to implement basic features already.

Write a class that allows you to interact with the url and that checks the url on page load and updates the webpage.

• [x] we need to be able to go through the url step by step and execute actions without having a nightmare of nested ifs so it would probably be best to represent the url in a json structure roughly like this. (note that the openDetailView function does not exist, its just an example)

  {
  rents: {
      handler: () => { this.appState.value.page = PageEnum.RENTS },
      children: {
          details: {
               handler: () => { openDetailView(URLHandler.getParam("student_id")) }
          },
       }
  },
  equipment: {...},
  calendar: {...}
  }

• [x] the class should provide a function like parseCurrentURL that takes the current url, parses it and then references it to the tree, executing the right handler function as it goes along
• [x] we also need a function like getParam which returns the value of any ? param in the url
• [x] to interact with the url we need a function that sets the url params (leaves the rest of the url untouched)
• [x] we also need a function to set/the/path in the url.. i think its fine if this just takes a the whole string and then writes it to the url, without changing the params of course
• [x] the most important thing here is that none of this causes a page reload: this is possible i have experimented with it you just need to find it