add deterministic methods and increase test coverage

[filintod]

Also from asyncio big PR, adding deterministic methods that are shared between sync/async context. Also increase test coverage of some previously not tested paths

current coverage:

============================================================================================================================== tests coverage ===============================================================================================================================
_____________________________________________________________________________________________________________ coverage: platform darwin, python 3.13.2-final-0 ______________________________________________________________________________________________________________

Name                                                    Stmts   Miss Branch BrPart  Cover   Missing
---------------------------------------------------------------------------------------------------
durabletask/__init__.py                                     1      0      0      0   100%
durabletask/aio/__init__.py                                 2      0      0      0   100%
durabletask/aio/client.py                                  96      9     18      4    85%   41-43, 115-120, 136, 148->151, 157
durabletask/aio/internal/__init__.py                        0      0      0      0   100%
durabletask/aio/internal/grpc_interceptor.py               28     15      4      0    41%   34-43, 53-54, 57-58, 61-62, 65-66
durabletask/aio/internal/shared.py                         23      0     12      0   100%
durabletask/client.py                                     143     18     24      4    83%   38, 54-55, 63-64, 68, 117-119, 121, 199-204, 232->235, 241, 278-280
durabletask/deterministic.py                               81      4     10      1    95%   134-135, 153, 224
durabletask/internal/grpc_interceptor.py                   29     16      4      0    39%   41-59, 62-63, 66-67, 70-71, 74-75
durabletask/internal/helpers.py                            70      5      6      1    92%   212-214, 243->exit, 245-246
durabletask/internal/orchestrator_service_pb2.py          254    238      2      1     7%   37-274
durabletask/internal/orchestrator_service_pb2_grpc.py     239    115      2      1    52%   16-17, 20, 181-183, 188-190, 195-197, 202-204, 209-211, 216-218, 223-225, 230-232, 237-239, 244-246, 252-254, 258-260, 264-266, 270-272, 276-278, 282-284, 289-291, 296-298, 303-305, 310-312, 317-319, 324-326, 331-333, 338-340, 345-347, 352-354, 359-361, 365-505, 523, 550, 577, 604, 631, 658, 685, 712, 739, 766, 793, 820, 847, 874, 901, 928, 955, 982, 1009, 1036, 1063, 1090, 1117, 1144, 1171, 1198, 1225
durabletask/internal/shared.py                             77      4     30      5    92%   41, 46-47, 103->106, 109->114, 150
durabletask/task.py                                       266     26     68     14    88%   35, 51, 70, 81, 97, 126, 159, 177, 190, 285, 293, 310, 313, 317, 335, 339, 352, 362, 370, 409, 540, 542, 544, 546, 548, 562->559, 605
durabletask/worker.py                                     844    126    328     53    82%   247-249, 251, 283, 307-310, 324-328, 336-337, 345-347, 354-355, 371->386, 374-385, 407, 408->exit, 439-442, 445-447, 452->454, 460-485, 494, 500->502, 511-530, 549-559, 567-570, 600-603, 643, 663, 693, 710, 750, 819, 846, 849->851, 872, 901->903, 906->909, 914, 944, 959->964, 988->992, 1006, 1038, 1047-1051, 1063, 1103-1107, 1118-1122, 1125->exit, 1153, 1169, 1180-1184, 1196-1200, 1202->exit, 1230, 1243->1245, 1252->1254, 1264->1266, 1271->1273, 1284-1285, 1367-1372, 1378, 1439->1445, 1451-1453, 1458-1460, 1469, 1471, 1499->exit, 1577-1595
---------------------------------------------------------------------------------------------------
TOTAL                                                    2153    576    508     84    73%

[filintod]

could probably later be moved to tox as a new test option

[filintod]

@acroca ptal

[filintod]

cover paths not tested previously, and can be used in the future when we add pydantic/others