Fix flexible time resolution in constraint fix_ratio_out_in_connection_flow

[gnawin]

Existing discussions:
#1119 (comment)
#1119 (comment)

Steps:

• use deterministic scenarios: change only t indice
• use stochastic scenarios: change only s indice
• with resolution of the delay that is multiples of the nodes
  - [ ] with resolution of the delay that is not multiples of the nodes? We should add a warning/comment that the delay has to be multiples of the nodes.
• add a parameter to control which resolution is used (make highest the default). Consider switch indices and maybe the constraint itself. Use the switch for tight and compact formulation in constraint unit flow capacity as an inspiration.
• unit test