Rewrite logic with system paths and imports in python

[tamarinvs19]

Description

1. Now all paths which we use in python code have row-string format. It helps when path contains special symbols with \.
2. Also we collecting in sys.paths all path for imported modules:
   • for import <module>
   • for from <module> import <smth>

Fixes #1562

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• Refactoring (typos and non-functional changes)

How Has This Been Tested?

Manual Scenario

Test for import modules

1. Create python project with the next files

# /mod1/a.py

def sum(x, y):
    return x + y

# /mod1/b.py

import a

def double_sum(x, y):
    return a.sum(x, y)

2. Generate tests for double_sum in b.py
3. Expected result: generated test

import sys
sys.path.append(r'..')
sys.path.append(r'..\mod1')
import builtins
import mod1
import unittest
import mod1.b


class TestTopLevelFunctions(unittest.TestCase):
    # region Test suites for executable mod1.b.double_sum
    
    # region
    
    def test_double_sum(self):
        actual = mod1.b.double_sum(True, False)
        
        self.assertEqual(1, actual)
    # endregion
    
    # endregion

Test for import modules with another import type from <modult> import <smth>

1. Create python project with the next files

# /mod1/submod1/a.py

def sum(x, y):
    return x + y

# /mod1/b.py
from submod1 import a

def double_sum(x, y):
    return a.sum(x, y)

2. Generate tests for double_sum in b.py
3. Expected result: generated test

import sys
sys.path.append(r'..')
sys.path.append(r'..\mod1')
import builtins
import mod1
import unittest
import mod1.b


class TestTopLevelFunctions(unittest.TestCase):
    # region Test suites for executable mod1.b.double_sum
    
    # region
    
    def test_double_sum(self):
        actual = mod1.b.double_sum(83, False)
        
        self.assertEqual(83, actual)
    # endregion
    
    # endregion

Checklist (remove irrelevant options):

• The change followed the style guidelines of the UTBot project
• Self-review of the code is passed
• The change contains enough commentaries, particularly in hard-to-understand areas
• No new warnings
• New tests have been added
• All tests pass locally with my changes