Add hint for disabled fuzzing control

[Vassiliy-Kudryashov]

Description

In case useFuzzing=false in settings.properties we disable corresponding UI control. Such a behavior may be not obvious for a user and we have to provide some explanation hint do explain why the control is dsabled and how to enable it.

To Reproduce

Specify useFuzzing=false in {home}/.utbot/settings.properties

Expected behavior

Fuzzing ratio control disabled with an explanation hint

Actual behavior

Fuzzing ratio control is just disabled

Visual proofs (screenshots, logs, images)