Implement GEOSEARCH[STORE] BYPOLYGON.

Valkey 9.0.0 implemented a new variant of `GEOSEARCH` where you supply
the verticies to an arbitrary polygon.

Since we can't modify the `geosearch` prototype using it is a little
wonky (you need to just pass empty strings for position and unit).

```php
$redis->geosearch('ca:cities', '', [
    -121.90, 39.65, -121.77, 39.65, -121.77, 39.80, -121.90, 39.80
], '');
$redis->geosearchstore('ca:cities', 'dst', '', [
    -121.90, 39.65, -121.77, 39.65, -121.77, 39.80, -121.90, 39.80
], '');
```

tests/RedisClusterTest.php

@@ -137,6 +137,7 @@ class Redis_Cluster_Test extends Redis_Test {
         $this->version  = $info['redis_version'] ?? '0.0.0';
         $this->is_keydb = $this->detectKeyDB($info);
         $this->is_valkey = $this->detectValkey($info);
+        $this->valkey_version = $info['valkey_version'] ?? '0.0.0';
     }
 
     private function findCliExe() {

tests/RedisTest.php

@@ -77,6 +77,7 @@ class Redis_Test extends TestSuite {
         $this->version = (isset($info['redis_version'])?$info['redis_version']:'0.0.0');
         $this->is_keydb = $this->detectKeyDB($info);
         $this->is_valkey = $this->detectValKey($info);
+        $this->valkey_version = $info['valkey_version'] ?? '0.0.0';
     }
 
     protected function haveCommand(string $cmd): bool {
@@ -90,6 +91,10 @@ class Redis_Test extends TestSuite {
         return version_compare($this->version, $version) >= 0;
     }
 
+    protected function minValkeyVersionCheck($version) {
+        return $this->is_valkey && version_compare($this->valkey_version, $version) >= 0;
+    }
+
     protected function mstime() {
         return round(microtime(true)*1000);
     }
@@ -6913,6 +6918,31 @@ class Redis_Test extends TestSuite {
         });
     }
 
+    public function testGeoSearchByPolygon() {
+        if ( ! $this->minValkeyVersionCheck('9.0.0'))
+            $this->markTestSkipped();
+
+        $this->addCities('ca:cities');
+
+        $res = $this->redis->geosearch('ca:cities', '', [
+            -121.90, 39.65, -121.77, 39.65, -121.77, 39.80, -121.90, 39.80
+        ], '');
+
+        $this->assertEquals(['Chico'], $res);
+    }
+
+    public function testGeoSearchStoreByPolygon() {
+        if ( ! $this->minValkeyVersionCheck('9.0.0'))
+            $this->markTestSkipped();
+
+        $this->addCities('ca:cities');
+        $this->assertEquals(1, $this->redis->geosearchstore('{gk}dst', 'ca:cities', '', [
+            -121.90, 39.65, -121.77, 39.65, -121.77, 39.80, -121.90, 39.80
+        ], ''));
+
+        $this->assertEquals(['Chico'], $this->redis->geosearch('{gk}dst', 'Chico', 1, 'm'));
+    }
+
     public function testGeoSearchStore() {
         if ( ! $this->minVersionCheck('6.2.0'))
             $this->markTestSkipped();

tests/TestSuite.php

@@ -15,6 +15,7 @@ class TestSuite
 
     /* Redis server version */
     protected $version;
+    protected string $valkey_version;
     protected bool $is_keydb;
     protected bool $is_valkey;