mosek_direct.py : Fixed iparam parsing and added support for Task.putparam

[Utkarsh-Detha]

Fixes:

In _apply_solver

• Call to putintparam was missing in the isinstance(option, str) conditional when parsing iparam. Fixed.
• Was calling option.pop('mosek') instead of option.pop(0) within the same conditional. Fixed.

Summary/Motivation:

A user wanted to be able to pass the value of ALL parameters as strings. MOSEK's optimizer API supports this through the Task.putparam function, which accepts a parameter name (string) and a value (also string).

Changes proposed in this PR:

• Users may pass string values to any parameter (SPAR, DPAR, IPAR) as long as they use generic parameter names

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