* op-proposer: ensure uniform proposal interval across restarts

closes https://github.com/ethereum-optimism/optimism/issues/11193

* move DGF query logic into FetchDGFOutput

* merge loopL2OO and loopDGF

* tweak comments

* Apply suggestions from code review
Co-authored-by: Sebastian Stammler <seb@oplabs.co>

* return err instead of defaulting to sending a proposak

flatten out control flow, remove shouldPropose var

* defer l.Log.Info("loop returning")

* improve error handling and logging

* fix logging syntax error

* make DGFContract interface

harmonize how network contexts are constructed

* modify test for new DGF behavior

* fix bugs in test code

* remove OutputRetryInterval flag

* handle gameCount = 0

* finish removing OutputRetryInterval

* driver waits one proposal interval for the first ever proposal

* do not create mock unecessarily

* do not create mockL2OOContract unecessarily

* wrap and return errors instead of logging and returning

* op-proposer: Switch to modern binding style for dispute game factory (#11472)

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Co-authored-by: Sebastian Stammler <seb@oplabs.co>
Co-authored-by: Adrian Sutton <adrian@oplabs.co>