Issue 49987: Add lineage endpoint to Rlabkey

[cnathe]

https://www.labkey.org/home/Developer/issues/issues-details.view?issueId=49987

Tasks:

• Rlabkey - experiment-lineage.api to get parent/child relationships - 3h
• Add RlabkeyTest case - 1h
• code review - 1h
• submit package to CRAN
• TC review and merge - 0.5h