When we add DRBs throught the configuration file, it will create dedicated DRBs, treating them as GBR Flow DRBs. This is useful for testing purposes in RFSIM and noS1

If it is a GBR flow, assign a dedicated DRB
If is is a NGBR flow, use an existing DRB, from the same PDU Session

Note: the case that we run out of DRBs is not handled yet, it is still a todo

Note: at this point we have a dedicated DRB per 5QI.

1. Added guard for exceeding DRB creation in ASN1 & RRC
2. Created function for finding the next available drb

Note: tested with 2 UEs in RFSIM mode