refactor(core)!: make getActionablePendingAction a view function

[beeb]

The front-end cannot make calls to functions that are not view (they could do a simulate but it's unergonomic).

Thus, the getActionablePendingAction has been made view and a new _getActionablePendingAction internal function has been added, for removing the empty items at the front of the queue.

NOTE: the coverage commands have been updated to ignore fuzzing and invariant tests, since they take too long with the local profile. Also, it would be good practice to have full coverage with only unit tests (without taking fuzzing into account).

[github-actions]

LCOV of commit 12b6695 during Coverage report #423

Summary coverage rate:
  lines......: 75.6% (606 of 802 lines)
  functions..: 83.4% (151 of 181 functions)
  branches...: 71.2% (245 of 344 branches)

Files changed coverage rate:
                                                           |Lines       |Functions  |Branches    
  Filename                                                 |Rate     Num|Rate    Num|Rate     Num
  ===============================================================================================
  src/UsdnProtocol/UsdnProtocolActions.sol                 |65.4%    185|77.8%    18|43.8%     64
  src/UsdnProtocol/UsdnProtocolCore.sol                    |81.6%    114|65.2%    23|76.7%     60
  test/unit/UsdnProtocol/utils/Handler.sol                 |80.8%     26|77.3%    22|    -      0

[samooyo]

ALL GOOD