[ModelicaSystemDoE] use OMCPath (#333)

* [ModelicaSystemDoE] add class

* [__init__] add class ModelicaSystemDoE

* [test_ModelicaSystemDoE] add test

* [ModelicaSystemDoE] add docstrings

* [ModelicaSystemDoE] define dict keys as constants

* [ModelicaSystemDoE] build model after all structural parameters are defined

* [ModelicaSystemDoE] cleanup prepare() / rename variables

* [ModelicaSystemDoE] cleanup simulate() / rename variables

* [ModelicaSystemDoE] cleanup get_solutions() / rename variables

* [test_ModelicaSystemDoE] update test

* [ModelicaSystemDoE] add example to show the usage

* add pandas as new dependency (use in ModelicaSystemDoE)

* [test_ModelicaSystemDoE] fix mypy

* add pandas to requirements in pyproject.toml

* [ModelicaSystemDoE] rename class constants

* [ModelicaSystemDoE] remove dependency on pandas

* no need to add aditional requirements
* hint how to use pandas in the docstrings
* update test to match code changes

* [ModelicaSystemDoE.simulate] fix percent of tasks left

* [ModelicaSystemDoE.prepare] do not convert all non-structural parameters to string

* [ModelicaSystemDoE] update set parameter expressions for str and bool

* [ModelicaSystemDoE] rename class constants

* [ModelicaSystemDoE] fix bool comparison

* [ModelicaSystemDoE] remove unused code

* [ModelicaSystemDoE] fix rebase fallout

* [ModelicaSystemDoE] fix rebase fallout

* [ModelicaSystemDoE] cleanup & extend & document dict key constants

* remove DICT_RESULT_FILENAME
* add comment
* add DICT_ID_STRUCTURE and DICT_ID_NON_STRUCTURE
* rename param_simple => param_non_structure

* [ModelicaSystemDoE] ensure any double quote in string variables is escaped

* [ModelicaSystemDoE] replace pathlib by OMCPath

* [ModelicaSystem/ModelicaSystemDoE] improve session handling

* add ModelicaSystem.session() - returns _getconn
* add ModelicaSystemDoE.session() - returns _mod.session()

reasoning:
* do not access private variables of a class
* limit chain access to (sub)data

* [ModelicaSystemDoE] fix path to resultfile

it does not exists at this point thus, resolve() and absolute() will fail

* [ModelicaSystemDoE] rename variables & cleanup

* [ModelicaSystemDoE] update variable handling / remove variables not needed

* [ModelicaSystemDoe] do not limit to OMCProcessLocal

* [test_ModelicaSystemDoE] update test definition for local/docker/WSL

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Co-authored-by: Adeel Asghar <[email protected]>

Author: syntron