Transition to composition API

[mchev]

Since issue #174 has been reopened, here is (once again) a proposal for the refactored system using the <script setup> syntax.

This is a new version of the old PR #175:

• Removed the dependency on popper.js, which was only used for dropdowns. The new dropdowns no longer require popper.
• The shared components have been left unchanged (except for the dropdown) and updated for the Composition API. Further enhancements could be made later to improve them.
• All pages now utilize the <script setup> syntax and Composition API.
• Using PascalCase for components based on https://vuejs.org/style-guide/rules-strongly-recommended.html recommendations
• Updated dependencies in order to run the fix-code-style script.

[LouiScura]

This is great! Should have been included in the last update...