Be able to extract value of components in UI

In tmc (utils.R) we have to break encapsulation to see what values are selected in the UI

```
extract_input <- function(varname, dataname, filter = FALSE) {
if (filter) {
paste0(varname, "-dataset_", dataname, "_singleextract-filter1")
} else {
paste0(varname, "-dataset_", dataname, "_singleextract-select")
}
}
```

NEST/teal.modules.general/issues/905 and possibly other shared code in the future.

This issue is to allow this behaviour without breaking encapsulation (it may involve adapting what we have e.g. a flag as to whether to return what we do now, or also the raw selected values, it may involve replacing with a simple select component in teal.devel to be created which doesn't interact with data) and then to create an issue in tmc to fix this.

NEST/teal.devel/issues/404 at the same time

Provenance:
```
Creator: nikolas-burkoff
```