More pause CLI commands

[mkysel]

Add more pause CLI commands by extending cmd/cli/main.go setPause and getPause to control app-chain gateway, settlement-chain gateway, payer registry, and distribution manager via new blockchain.SettlementChainAdmin and updated blockchain.AppChainAdmin.

• Expand CLI pause targets in main.go by wiring setPause/getPause to blockchain.AppChainAdmin and a new blockchain.SettlementChainAdmin, with setupSettlementChainAdmin handling settlement-chain admin construction.
• Add settlementChainAdmin in settlementChainAdmin.go to bind to SettlementChainGateway, PayerRegistry, and DistributionManager and implement get/set pause with on-chain UpdatePauseStatus transactions and event parsing.
• Extend appChainAdmin in appchainAdmin.go to bind AppChainGateway and add GetAppChainGatewayPauseStatus/SetAppChainGatewayPauseStatus.
• Add pause parameter keys in parameterAdmin.go.
• Update configuration for gateway and distribution manager addresses in chainConfig.go, options.go, validation.go, and extend target parsing in cliOptions.go; update test config in config.go.
• Add and adjust tests in settlementchainAdmin_test.go and appchainAdmin_test.go.

📍Where to Start

Start with setPause, getPause, and setupSettlementChainAdmin in main.go, then review NewSettlementChainAdmin and pause setters/getters in settlementChainAdmin.go.

Changes since #1090 opened

• Added contract address validations to CLI setup functions [78fb926]
• Added TODO blocks for future gateway address validations [78fb926]
• Updated error message in config.Target.UnmarshalFlag method to include all valid target values [1644423]
• Added fallback configuration logic in config.fillConfigFromJson function [174dee8]

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Macroscope summarized 174dee8.

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