Fixes #1943 - add polyline option for delineation by line

[harper-wavra]

• option to delineate by polyline instead of a single line

If wanting to test before https://code.usgs.gov/StreamStats/web-services-and-apis/ss-pourpoint/-/merge_requests/16 is merged and deployed. You will need to run Pourpoint branch HW-21 locally and update the PourpointServices to 'http://127.0.0.1:8000' in the appconfig.

[amedenblik]

We should redeploy SS-Pourpoint after this is merged, to include https://github.com/USGS-WiM/StreamStats/pull/1952

[harper-wavra]

Deployed to https://dev.streamstats.usgs.gov/sc-runoff/