data_extract_spec objects should have an optional submit button to prevent needless re-render

proposal:

```r
data_extract_spec(
dataname,
select = NULL,
filter = NULL,
reshape = FALSE,
sub_btn = FALSE,
)
```

When `sub_btn = TRUE`, then the output will listen to the `actionButton` rather than the changes to any of the `selectInputs`.


For example, If user will need to select 10 different values to filter in a filter_spec, that would be 10 needless re-renders of the output. A submit button will solve this.

Provenance:
```
Creator: junlue
```