Implement individual-level line plots (phase 1)

Phase 1 must haves:

X-axis parameter selector: constrain to time-related variables (date, age, study timepoint)...these could be continuous or discrete (ie, 5 study timepoints). possibly think about defining this parameter on a per-study basis (in the presenter file? or with annotations in the .owl?)
Y-axis parameter selector: constrain to continuous variables (we decided to handle the categorical vars in a separate strip plot viz tool, see https://github.com/VEuPathDB/web-eda/issues/1527)

Phase 1 nice to haves:

Stratification identifier (ie, facet plots by PID vs HHID, etc)
Sorting based on other variable(s) -- through faceting 2.0 (https://github.com/VEuPathDB/web-eda/issues/1501), which we anticipate rolling out BEFORE individual-level line plots

Phase 2:

Do not start implementing until individual level line plot mockups receive final sign off in EDA UX meeting

VEuPathDB / web-eda