more legible geo-types debug output (WKT-ish)

FIXES #564

Note: Most of the output is valid WKT, but not all of it is.
For example, there is no RECT or TRIANGLE type in standard WKT.

And there are certain invalid representations you can make in geo that
are not valid WKT, but for a debug output format we still need to print
*something*

e.g. a polygon with interiors but no exterior: `POLYGON(EMPTY,(1 2,2 4))`

geo-types/CHANGES.md

@@ -1,5 +1,10 @@
 # Changes
 
+## UNRELEASED
+
+- Add more concise Debug output for geometries (like WKT).
+  NOTE: because geo-types allows some representations which are not supported by standard WKT, not all debug output is valid WKT. Do not attempt to treat debug as a stable format - it's unsuitable for interacting with programmatically. See the [`wkt` crate](https://crates.io/crates/wkt) for that.
+
 ## 0.7.15 - 2025-01-14
 
 - Implement `RTreeObject` for `Triangle`.