[x] Delete map projection attrChgCallbk from triggering map-change event. Allow map-extent to react to map-projectionchange event, enable/disable according to projection match.
[x] Change initialization logic for opacity, so that layer- and map-extent opacity value is maintained through map-projectionchange event.
[x] Remove MapMLLayer.validProjection attribute and flawed logic.
[x] Prettier formatting change only in multipleExtents.test.js
[x] Remove use of validProjection by layer context menu, was wrong anyway(?)
[x] Add waitfortimeout of 500ms in customTCRS.test.js (100ms was not enough)
[x] Add test for simple projection change.
[x] Add test for opacity through map-projectionchange - quite laggy, needed to waitfortimeout(1000) (at least)
[ ] Fix history after map-projectionchange not possible need to rewrite history
[x] Update map-extent connectedCallback to throw if the units="projection_name" projection_name value is not a defined projection via mapml-viewer.defineCustomProjection
Closes #910
Fix history after map-projectionchangenot possible need to rewrite historymapml-viewer.defineCustomProjection