Move gas fee settings for retirement operations in the config.

[kirill-tolochko]

Problem description

Currently user is unable to create a retirement contract or retire some tokens if operations in hedera are more expensive than value in some setting in the code. This setting should be put in the config.

Requirements

• Make config for gas fee for retirement operations.

Definition of done

• Enhancements are implemented as per above
• Documentation updated (including the screenshots)

Acceptance criteria

User is able to set up his personal boundaries for gas fee in the config file