Refactor Saas naming, structure and modules

- Add more documentation.
- Use `main.scss` instead of importing components individually. This
  improves productivity without compilation errors due to missing
  imports and allows for easier future file/folder changes and
  refactorings inside `./styles`.
- Use partials with underscored naming. Because it documents that the
  files should not be individually imported.
- Introduce `third-party-extensions` folder to group styles that
  overwrites third party components.
- Refactor variable names from generic to specific.
- Use Sass modules (`@use` and `@forward`) over depreciated `@import`
  syntax.
- Separate font assets from Sass files (`styles/`). Create `assets/`
  folder that will contain both.
- Create `_globals.css` for global styling of common element instead of
  using `App.vue`.

src/presentation/components/Shared/Dialog.vue

@@ -31,12 +31,11 @@ export default class Dialog extends Vue {
 </script>
 
 <style scoped lang="scss">
-@import "@/presentation/styles/fonts.scss";
-@import "@/presentation/styles/colors.scss";
+@use "@/presentation/assets/styles/main" as *;
 
 .dialog {
   color: $color-surface;
-  font-family: $normal-font;
+  font-family: $font-normal;
   margin-bottom: 10px;
   display: flex;
   flex-direction: row;