refactor(task groups): use a less mixin for the inputs

Conflicts:
	client/scripts/task/styles.less
fix(filters): correct the active state CSS class

Related to: CAM-2779
impr(layouts): store the selected layout in the URL

Related to: CAM-2943
impr(layout): only the toggler should trigger collapse / expand

Related to: CAM-2943
impr(styles): move mixins to an imported less file
fix(filter): change modal header according to access rights

Related to: CAM-2790
impr(filters task): increase the clickable area to select a task

Related to: CAM-2975
feat(task): add a link to open task in standard layout

Related to: CAM-2976