Robyn Bugs in Allocator and Response Functions

Attention: @laresbernardo, @gufengzhou , @michellegrushkometa

In the demo.R, if I run the following code it does not use media spend data to document the (mean, %share) spend in the outputs. Currently using (v3.12.1 - the latest I believe).

Instead, it uses whatever is in the paid_media_selected, which is paid_media_vars for the demo example. We know paid_media_vars can have impressions, spend, clicks everything mixed up. So the spend metrics [here](https://github.com/facebookexperimental/Robyn/blob/5915aa9d5d31d8947a274aa00fdf30b8947823e5/R/R/allocator.R#L215) (line: 215 to 241) will have mixed units ... thus not correct and makes no sense. Or am I thinking it wrong?

Given such, can I trust any of the numbers that this function outputs? Or its just the spend numbers which are off, and ROAS, or CPA will be correct?

```
attribution_window_start_date <- '2018-10-01'
attribution_window_end_date <- '2018-12-31'

allocator_growth <- robyn_allocator(
InputCollect = InputCollect
, OutputCollect = OutputCollect
, scenario = "max_response"
, select_model = '3_56_25'
, channel_constr_low = 0.5
, channel_constr_up = 2
, date_range = c(attribution_window_start_date
, attribution_window_end_date)
)

print(allocator_growth$plots[2])
```

Thanks