Feature request: SVG output for large visualizations

### Summary

When generating visualizations with large inputs on chart operations such as: (Scatter, Heatmap, ...), the generated SVG output for the download file is escaped. It might be useful to have the ability to download the SVG as a file.

Although viewing the SVG can be achieved by changing the output threshold in the options, this may not be clear to the user.

### Example

Sample python script generating 100k random data points

```
import random

with open('randomdata.txt', 'a') as data_file:
line_count = 0
while (line_count < 100000):
data_file.write('{0}, {1}\n'.format(random.randint(1,100), random.randint(1,100)))
count = count + 1
```
Sample chart generation

Sample output from downloaded file

```
X: 20
Y: 91
X: 47
Y: 12
X: 25
Y: 21
...
```

The issue names large Scatter and Heatmap visualizations, the SVG output threshold option, and the downloaded file behavior, but no files or tests. Start by reproducing a large visualization and inspecting how its download output changes with the threshold option. Done means users can download the visualization as an SVG file rather than receiving escaped text.

Written by the indexing model from the issue text.