Adding tasks

We provide five common tasks for clinical prediction by default:

No	Task	Frequency	Type
1	ICU Mortality	Once per Stay (after 24H)	Binary Classification
2	Acute Kidney Injury (AKI)	Hourly (within 6H)	Binary Classification
3	Sepsis	Hourly (within 6H)	Binary Classification
4	Kidney Function(KF)	Once per stay	Regression
5	Length of Stay (LoS)	Hourly (within 7D)	Regression

Cohorts created in YAIB are built to be easily adaptable. For example, predicting ordinal KDIGO stage rather than binary presence/absence of AKI is as simple as changing the outcome variable from aki to kdigo. More substantial changes to the task are also supported. If the general setup (i.e., covariates, exclusion criteria, etc.the outcome should be created as a clinical concept in ricu which can then simply be used as the outcome variable. If covariates, exclusion criteria, or prediction times change, existing helper functions can be utilized. See the existing task definitions for further examples) remains the same but a novel outcome should be predicted,