Running tests fails on Windows

[dragoi75]

Describe the bug
Running the generated tests on Windows fails due to single quotes in the compile command.

To Reproduce
Steps to reproduce the behavior (on Windows):

1. Run TestSpark via Run IDE for UI Test
2. Generate tests with TestSpark for an arbitrary Java class
3. Hit Run All
4. The IDE gives the following error in the console output:

INFO org.jetbrains.research.testspark.core.test.java.JavaTestCompiler - Exit code: '1'; Execution message: 'The filename, directory name, or volume label syntax is incorrect.

Additional context

• The issue is due to the single quotes introduced in Add quotes around compilers' filepaths #389. My fix for Windows was to replace "'$javac'", with "\"$javac\"", (double quotes instead of single quotes). I don't know if the replacement breaks the in macOS / Linux.
• I only tested it for Java, not for Kotlin, but I expect the same behavior.