Dashboard Variables - location on dashboard - simple and flexible method for dynamic arrangement

**Why is this needed**: Users want to increase vertical real estate by placing variables along the side, or de-emphasize variables by placing them on the bottom, or mimic the UI of another tool they are familiar with in a high-turnover low training environment (e.g. tier 1 operations), or more tightly couple sets of variables near the panels or rows where they are relevant. **What would you like to be added**: - define a new construct "Variable Group" which is a collection of Variables - Under dashboard settings, variables tab, on right side top have a button to add a Variable Group - Below that, list of Variable Group sections, each of which has the desired variables arranged in order. Default is a single Variable Group that any defined variables go into (for backward compatibility). - For each variable group, have a Position setting, with these options: 1. anchor to top (default for upgrade path with backward compatibility) 2. anchor to left 3. anchor to right 4. anchor to bottom 5. arrange like panel - Each Variable Group Section can be drag/dropped to rearrange order of Variable Groups just like for existing variables or dashboard panels. - When multiple variable groups have the same Position setting, they are horizontally adjacent (for top/bottom anchors) or vertically adjacent (for left/right anchors) but remain as separate boxed entities rather than merging the contents of the variable lists. This empowers dashboard admins with a little more esthetic control, and offers flexibility to define a title for Variable Groups to display in each variable grouping. - Variable Groups with position method "arrange like panel" are placed in a default location on the dashboard, and resized and relocated just like panel visualizations - Variable Groups with position method cannot be placed in repeating rows (because that would duplicate the nested variables). This might be reconsidered in a future version to implement more advanced variable interpolation. - Should also …