[refactor]: refactor handlers to be expandable

[willianrod]

Problem

The current architecture is expandable but requires a lot of configurations, we need it to be expandable with less configuration. This will allow ODeck to expand features very fast.

Possible solution

I still thinking about that, but I'm open to suggestions.

Minimum requirements

• For every new handler, we should touch a single file
• The handler should be localized using i18n
• Registering the handlers should be done automatically
• Every handler should add a new group to the sidebar

[willianrod]

Refactor is in progress complete. Got everything working in the new architecture. To develop a new handler you'll have to change one single file and add translations.

In some cases, some handlers will require some kind of configuration like defining an API key to make API requests. To allow this, I'll develop a settings page and only load the handler if the API key is defined.

[willianrod]

Refactor completed. Will be available on release v0.0.5 #32