feat(wmg): implement gene length normalization

[atarashansky]

Reason for Change

• #TICKET_NUMBER
• If the reason for this PR's code changes are not clear in the issue, state value/impact

Changes

• add
• remove
• modify

Testing steps

• Either list QA steps or reasoning you feel QA is unnecessary
• Describe how you made sure to know that your changes worked. Should allow someone else to go verify your code without in depth knowledge.
• "Unit tested only", "tested in rdev by a, b, c, verifying feature worked by... ", "manually ran pipeline locally with these results: ..."

Notes for Reviewer

[kaloster]

LGTM for readability!