Add fileKey rotation to GridFSBucketAdapter (#6768)

* add fileKey encryption to GridFSBucketStorageAdapter

* remove fileAdapter options from test spec

* ensure promise doesn't fall through in getFileData

* switch secretKey to fileKey

* add fileKey rotation for GridFSBucketAdapter

* improve catching decryption errors in testcases

* add testcase for rotating key from oldKey to noKey leaving all files decrypted

* removed fileKey from legacy test links. From the looks of the tests and the fileKey was appended to links. This key is now an encryption key

* clean up code

* make more consistant with FSAdapter

* use encryptionKey instead of fileKey

* Update ParseFile.spec.js

revert

src/Options/Definitions.js

@@ -149,6 +149,10 @@ module.exports.ParseServerOptions = {
     action: parsers.booleanParser,
     default: false,
   },
+  encryptionKey: {
+    env: 'PARSE_SERVER_ENCRYPTION_KEY',
+    help: 'Key for encrypting your files',
+  },
   expireInactiveSessions: {
     env: 'PARSE_SERVER_EXPIRE_INACTIVE_SESSIONS',
     help: 'Sets wether we should expire the inactive sessions, defaults to true',