Modular component scripts

[sebnitu]

Problem

Current Vrembem JavaScript components are written in a single file. This can make it hard to understand their features, test and keep organized.

Solution

This PR re-writes Vrembem's JavaScript components to be more module. Each components module entry is through their index.js file where a factory function written in ES6 classes is defined. From there, all functionality is split into their own module files and shared features between modules has been moved into @vrembem/core in their own modules.

A few of the now shared @vrembem/core modules include:

Modules	Exports
accessibility	{ setInert, setOverflowHidden, setTabindex }
focus	{ focusTarget, focusTrigger, FocusTrap }
getElement	{ getElement }
moveElement	{ moveElement }
transition	{ openTransition, closeTransition }

Ref #257