[BUG] ISA-Json writing @id referencing might lose information

[HLWeil]

Describe the bug
Characteristics are not correctly handled between samples in different assays/studies before being written to ISA-Json. This can lead to lost information.

To Reproduce

• Create an ARC
• Add study
  • Add table with output sample
• Add assay
  • Add table with the same input sample
  • Add characterstic
• Export to ISA json making use of useIDReferencing

@xiaoranzhou