* Update icons for summary and ensemble templates
* Icons for regression and decline
* #10374 LineEditor: Hide the placeholder widget when not used
* #10376 Assign a case ID to delta summary case
* Do not show decline range text in plot
Enable c++20 in top level cmake. Keep c++17 for GrpcInterface, as the protoc tool does not work with c++20.
Several code adjustments to fix compiler issues.
* Ensemble plot templates now have .erpt extension and new icon
* Default plot templates are given a checkmark overlay on the icon
* Context menu has been cleaned up a bit
* Old default template is really just the last used template. Rename it.
* Add max. recursive depth setting in preferences for plot template searches
* Only create plots based on correct template type when importing ensembles or single cases
* Support creating new plot from template explorer
* Update last used template when creating a new plot from a template
* Remove obsolete template commands
Use first object in object list when creating plots for templates and a case is selected. (use first well in well list, first group in group list, ...)
* Always create the reference string
