Languagepp using Command ACM PC2

A PR is created to provide the detail about the current progress and possibility of using command to execute and compile code of Assignment.

Pull Request Link: https://github.com/BilalZaib/AutoGrader/pull/93

Advantages:

1. More languages can be added.
2. Use subprocess and popen for execution (separate process), we can limit the process privileges.
3. Can have pytest for execution.
4. Can take input as FILE, STDIN, ARGS and PyTest (Not coded yet).

Disadvantages

1. Architectural changes in the code.
2. run.py will be updated.
3. Handle pytest as exception (it input type is different), I think this can be handled.
4. Using FILE, STDIN, ARGS is not good. PyTest test cases are the beauty (Easy to create and manage).