Prepend encryption flag iue to platform metadata

Sending extra metadata in the handshake will allow us to detect when
encryption is enabled. `iue` for In-Use Ecnryption was chosen to save
bytes (as metadata will be truncated if it exceeds byte limit)

Author: paulinevos

src/ValueObject/DriverOptions.php

@@ -129,6 +129,10 @@ private function withDriverInfo(array $driver): self
             $mergedDriver['platform'] = $driver['platform'];
         }
 
+        if ($this->isAutoEncryptionEnabled()) {
+            $mergedDriver['platform'] = trim(sprintf('iue %s', $driver['platform'] ?? ''));
+        }
+
         return new self(
             typeMap: $this->typeMap,
             builderEncoder: $this->builderEncoder,

tests/ValueObject/DriverOptionsTest.php

@@ -88,18 +88,67 @@ public static function provideOptions(): \Generator
             ]
         ];
 
+        yield 'encryption enabled' => [
+            ['autoEncryption' => [
+                'keyVaultNamespace' => 'foo',
+            ]],
+            [
+                'typeMap' => [
+                    'array' => BSONArray::class,
+                    'document' => BSONDocument::class,
+                    'root' => BSONDocument::class,
+                ],
+                'autoEncryption' => [
+                    'keyVaultNamespace' => 'foo',
+                ],
+                'builderEncoder' => new BuilderEncoder(),
+                'driver' => [
+                    'name' => 'PHPLIB',
+                    'platform' => 'iue',
+                ]
+            ]
+        ];
+
+        yield 'encryption enabled with platform' => [
+            [
+                'autoEncryption' => [
+                'keyVaultNamespace' => 'foo',
+                ],
+                'driver' => [
+                    'platform' => 'bar'
+                ]
+            ],
+            [
+                'typeMap' => [
+                    'array' => BSONArray::class,
+                    'document' => BSONDocument::class,
+                    'root' => BSONDocument::class,
+                ],
+                'autoEncryption' => [
+                    'keyVaultNamespace' => 'foo',
+                ],
+                'builderEncoder' => new BuilderEncoder(),
+                'driver' => [
+                    'name' => 'PHPLIB',
+                    'platform' => 'iue bar',
+                ]
+            ]
+        ];
+
         yield 'extra options' => [
             [
                 'typeMap' => [],
                 'builderEncoder' => new BuilderEncoder(),
                 'autoEncryption' => [],
                 'some' => 'option',
-                'some_other' => ['option' => 'too']
+                'some_other' => ['option' => 'too'],
+                'driver' => ['platform' => 'foo',]
             ],
             [
                 'builderEncoder' => new BuilderEncoder(),
                 'driver' => [
                     'name' => 'PHPLIB',
+                    'platform' => 'foo',
                 ],
                 'some' => 'option',
                 'some_other' => ['option' => 'too']