Remember Test Sources root choice and suggest as default #1010

[Vassiliy-Kudryashov]

Description

Persist the history of recent used source roots to suggest them somewhere on the top of the list.

Fixes #1010

Type of Change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Automated Testing

See org.utbot.intellij.plugin.ui.utils.RootUtilsTest

Manual Scenario

1. Open a project with several modules with several test source roots in each.
2. Generate some tests for the first module (select not-default source root).
3. Generate soem tests for the second module (select not-default source root there too).
4. Call "Generate" action for the first module. The module selected in 2. should be preselected.

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