Add pattern tests for transaction-statistics API

...ransaction_statistics/negative/invalid_block_num.pat.json

...saction_statistics/negative/invalid_block_num.tavern.yaml

...ransaction_statistics/negative/invalid_timestamp.pat.json

...saction_statistics/negative/invalid_timestamp.tavern.yaml

...ransaction_statistics/negative/unknown_direction.pat.json

...saction_statistics/negative/unknown_direction.tavern.yaml

...et_transaction_statistics/negative/unknown_order.pat.json

...transaction_statistics/negative/unknown_order.tavern.yaml

...transaction_statistics/positive/change_direction.pat.json

...nsaction_statistics/positive/change_direction.tavern.yaml

...get_transaction_statistics/positive/change_range.pat.json

..._transaction_statistics/positive/change_range.tavern.yaml

...vern/get_transaction_statistics/positive/default.pat.json

...n/get_transaction_statistics/positive/default.tavern.yaml