Firewall_rules diff mode support (#407)

• fw_rules diff init

• comment support

• sanity fix

• remove redundant

• integration tests for fw_rules diff mode

• 1.3- integration tests for firewall_rule diff

• 1.4+ long string linter fix

• 1.3- long string linter fix

• long str rework

• typo

• Remove commented-out diff block in YAML file

removed comments

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Co-authored-by: Daniil Baturin <daniil@baturin.org>