Sort versions in the documentation version picker appropriately. (#16966

)

Fixes #16964 

This adds a proper sorter for versions which takes into account semantic
versions, rather than just relying on localeCompare.

changelog.d/16966.doc

@@ -0,0 +1 @@
+Fix the sort order for the documentation version picker, so that newer releases appear above older ones.

docs/website_files/version-picker.js

@@ -100,10 +100,30 @@ function sortVersions(a, b) {
     if (a === 'develop' || a === 'latest') return -1;
     if (b === 'develop' || b === 'latest') return 1;
 
-    const versionA = (a.match(/v\d+(\.\d+)+/) || [])[0];
-    const versionB = (b.match(/v\d+(\.\d+)+/) || [])[0];
+    // If any of the versions do not confrom to a semantic version string, they
+    // will be sorted behind a valid version.
+    const versionA = (a.match(/v(\d+(\.\d+)+)/) || [])[1]?.split('.') ?? '';
+    const versionB = (b.match(/v(\d+(\.\d+)+)/) || [])[1]?.split('.') ?? '';
 
-    return versionB.localeCompare(versionA);
+    for (let i = 0; i < Math.max(versionA.length, versionB.length); i++) {
+        if (versionB[i] === undefined) {
+            return -1;
+        }
+        if (versionA[i] === undefined) {
+            return 1;
+        }
+
+        const partA = parseInt(versionA[i], 10);
+        const partB = parseInt(versionB[i], 10);
+
+        if (partA > partB) {
+            return -1;
+        } else if (partB > partA) {
+            return 1;
+        }
+    }
+
+    return 0;
 }
 
 /**