Pass context in beforeDelete, afterDelete, beforeFind and Parse.Cloud.run. (#6666)

* add context for following hooks.
1. beforeDelete
2. afterDelete
3. beforeFind
4. Cloud Function

* revert un-necessary code change.

* fix: failing test cases.

* fix: failing test cases.

* fix: failing test cases.

* fix: failing test cases.

* fix: failing test cases.

* fix: failing test cases.

* fix: failing test cases.

* review changes

* revert changes

* revert changes

* review changes

* lint changes

* review changes

src/middlewares.js

@@ -33,6 +33,7 @@ export function handleParseHeaders(req, res, next) {
     dotNetKey: req.get('X-Parse-Windows-Key'),
     restAPIKey: req.get('X-Parse-REST-API-Key'),
     clientVersion: req.get('X-Parse-Client-Version'),
+    context: {},
   };
 
   var basicAuth = httpAuth(req);
@@ -103,6 +104,10 @@ export function handleParseHeaders(req, res, next) {
         info.masterKey = req.body._MasterKey;
         delete req.body._MasterKey;
       }
+      if (req.body._context && req.body._context instanceof Object) {
+        info.context = req.body._context;
+        delete req.body._context;
+      }
       if (req.body._ContentType) {
         req.headers['content-type'] = req.body._ContentType;
         delete req.body._ContentType;