feat(Execution workflow): CSI-UTR - report Format 04 BED file in workflow (per-PAS fractional relative usage)

Parent issue - https://github.com/iRNA-COSI/APAeval/issues/382

Per updated execution workflow [output specifications](https://github.com/iRNA-COSI/APAeval/blob/main/execution_workflows/execution_output_specification.md), We need CSI-UTR to report the per-PAS fractional relative usage in a format 04 BED file.

CSI-UTR calculates a number of relative usage metrics, but the one that fits the format 04 convention is the 'PSI' metric which is equivalent to the percent a polyA site is used relative to total expression of PAS in that gene/terminal exon. If reported on the % scale (0-100) this needs to be converted to a fraction by dividing by 100.