[Angular - NgRx - SCSS] Create tagged template function for services to encode URI pieces

[lindakatcodes]

In all the service calls to the GitHub API, we're currently encoding multiple strings pieces and then constructing the URL to send.

We'd like to create a tagged template function that can be used to construct the URLs, and make the services a bit cleaner. The goal of this ticket is to create the tagged template function and use it in all the service calls.

More on tagged templates here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals#tagged_templates