Accept context via header X-Parse-Cloud-Context (#7437)

* failing testcase

* add header

* switch to X-Parse-Cloud-Context header

* add back blank line that lint removed

* test replacing context header with body context. Add support for setting body with json string

* add back blank line

* cover error when _context body is wrong

* Update middlewares.js

* revert accidental status change

* make sure context always decodes to an object else throw error

* improve context object check

Co-authored-by: Antonio Davi Macedo Coelho de Castro <adavimacedo@gmail.com>

CHANGELOG.md

@@ -137,6 +137,8 @@ ___
 - Fix select and excludeKey queries to properly accept JSON string arrays. Also allow nested fields in exclude (Corey Baker) [#7242](https://github.com/parse-community/parse-server/pull/7242)
 - Fix LiveQuery server crash when using $all query operator on a missing object key (Jason Posthuma) [#7421](https://github.com/parse-community/parse-server/pull/7421)
 - Added runtime deprecation warnings (Manuel Trezza) [#7451](https://github.com/parse-community/parse-server/pull/7451)
+- Add ability to pass context of an object via a header, X-Parse-Cloud-Context, for Cloud Code triggers. The header addition allows client SDK's to add context without injecting _context in the body of JSON objects (Corey Baker) [#7437](https://github.com/parse-community/parse-server/pull/7437)
+
 ___
 ## 4.5.0
 [Full Changelog](https://github.com/parse-community/parse-server/compare/4.4.0...4.5.0)