fix: keep layer visibility after clicking on toggle all (#2439)

fix #2430

Not exactly sure how to make this DRY. What we want is to mark the layer
visibility as "controlled by user" as soon as they click on a
show/hide/showAll/hideAll button, so we do not try to infer the
visibility from the from/toZoom settings.

umap/static/umap/js/modules/browser.js

@@ -254,6 +254,7 @@ export default class Browser {
       if (datalayer.isVisible()) allHidden = false
     })
     this._umap.eachBrowsableDataLayer((datalayer) => {
+      datalayer._forcedVisibility = true
       if (allHidden) {
         datalayer.show()
       } else {