[Data] Update Spenders and Categories via Javascript

[eryc-cc]

In the latest updates made on PR #18, the expected data format for both spenders and categories is an Object with key and name attributes:

let categories = {
  creditcard: {
    name: 'Credit Card',
    key: 1651056654886
  },
  home: {
    name: 'Home',
    key: 1651056656009
  }
};

let spenders = [
  {
    name: 'Spender One',
    key: 1651056656974
  },
  {
    name: 'Spender Two',
    key: 1651056657897
  }
];

The app needs to initialize with the Spenders and Categories as an Object and then:

• Render the select options according to the data available.
• Have the option to Add/Update/Remove spenders and categories dynamically.
  • Update transactions(bills) when removing a spender or category
• Update the calculations accordingly
• Update the way transactions are rendered