[css-grid][META] Auto-placement Improvements

[fantasai]

Opening this to track possible improvements in auto-placement. Might need to refactor the issues later.

• Default areas for auto-placement ([css-grid-3] Adding auto placement override capibilities #8655 & [css-grid] Default Grid Columns, Rows, and Areas #4002)
• Calculations for auto-placement ([css-grid-3] Adding auto placement override capibilities #8655)
• Auto-placement into named areas ([css-grid] More granular auto placement from grid container element #7399 & [css-grid] 'auto' keyword should work with name grid lines/areas #3243)
• Skipping certain cells ([css-grid] Mark some cells as busy so they are skip in auto-placement #4012)
• Filtering auto-placement options ([css-grid] Auto-placement aligning to a named line #796 & [css-grid-3][masonry] Prioritize tracks that don't create overflow #10088 & [css-grid-3] Designer/developer feedback on masonry layout #10233 (comment)) [RESOLVED; needs edits]

I think that last one came up during the original design of Grid L1, so there's probably additional discussion on it somewhere...