[BulkRNASeq] Handle cases where distinct group names resolve to the same R safe name

[J-81]

Description

Factor value strings can collapse into the same R safe strings.
E.g. "p53+/Fbxw7+/-" and "p53-/Fbxw7-/-" Both collapse into "p53..Fbxw7..."
This breaks DESeq2 R scripts.

Steps to Reproduce

1. Run processing on OSD-432

Expected Behavior

R DESeq2 script safely handles factor values when resolve to multiple original names converting to the same safe name.

Actual Behavior

R DESeq2 script raises an exception.

Impact on Data

Non silent edge case, thus no released processed data should be impacted.

Blocks processing for 1 dataset at start of this ticket.

Additional Context

Provide any additional information or context that might be relevant to the issue.

Possible Solution (optional)

Introduce an integer or letter to each unique original factor value. This character will differentiate all factor values when converting to and using R safe names.