Allow for multiple marker/index tables when running getCohortSequence

[daniellenewby]

A user can create a cohort table containing multiple marker drugs for analysis so if i have 20 drugs i can merge them all into one cohort i.e

cdm[["test_drugs"]] <- union_all(cdm[["test_drugs"]], cdm[["antidep_moins"]] %>% dplyr::mutate(cohort_definition_id = 19, cohort_name = "Antidepressants NS Monoamine oxidase inhibitors")) %>% CDMConnector::computeQuery()

However if you have lots of drugs this table becomes too large and you get an error message:
"Error: cannot allocate vector of size 4419.0 Gb"

Suggestion:
At the moment a user can only specify one index and one marker table but i think we should allow for multiple ones in the argument lie this:

cdm <- CohortSymmetry::getCohortSequence(cdm = cdm,
name = "ache_inhibitors_com_test_drugs",
dateRange = c(starting_date, ending_date),
indexTable = "ache_inhibitors_com",
markerTable = c( "test_drugs1", "test_drug2" etc),
daysPriorObservation = 365,
indexWashout = 365,
markerWashout = 365,
timeGap = 365)