escoSimZeroInflate: Simulate noisy observed count matirx via adding more zeros...
In JINJINT/ESCO: Simple Simulation of Single-cell RNA Sequencing Data

A logistic function is used to form a relationshop between the expression level of a gene and the probability of dropout, giving a probability for each gene in each cell. These probabilities are used in a Bernoulli distribution to decide which counts should be dropped.

1	escoSimZeroInflate(sim, trial, verbose)

`sim`	SingleCellExperiment to add dropout to.
`trial`	the index of trial of simulation, all trials share the same truth but the noise is added independently for each trial
`verbose`	whether to print the process or not