:bug: Fix rendering highlight decoration on single line as line
Refactor decorations retrieval methods to use a generic one
Add a getActiveMinimap method
Handle decorations added with a class param

In that case the class param is transformed in the corresponding
selector and scoped into the `.minimap` class.
Add some delegations to the editor methods

The purpose here is to be able to pass the minimap view
as an editor wherever decorations are added. It’s a poor man solution
to avoid duplicating code from other plugin.