New function CST_Start

This issue is to create a new function to retrieve the data that calls Start and directly transforms the output into an 's2dv_cube' object similarly CST_Load does.

An example of the function structure is the following:

CST_Start <- function(...) {
  data <- Start(...) 
  data <- as.s2dv_cube(data)
  return(data)
}

The developments needed are the following:

• Create the new function CST_Start
• Add a warning in CST_Load function in order that the users preferably use CST_Start
• Substitute the loading with CST_Load for CST_Start of the vignettes in CSTools
• Substitute the loading with CST_Load for CST_Start of the examples in CSTools
• Create new sample data with CST_Start
• Substitute the loading with CST_Load for CST_Start of the vignettes in CSIndicators
• Substitute the loading with CST_Load for CST_Start of the examples in CSIndicators