introduce tests

added tests to prevent regression

Dev spatial data menu to explore dataset

chore: implemented test to avoid regression

bugfix: mouseOver directive not capturing scanning region properly
feat: reworked region menu component
feat: introduced landmark component
chore: reworked spatial search endpoint

update patch notes

bugfix: angular aot appears to not able to import {x as a} from './a'…

use web component for dataset preview

Feat/opacity slider

bugfix menu collapse

fixes https://github.com/HumanBrainProject/interactive-viewer/issues/466