[BUG] Data table download/export freeze ui for large dataset

[jolevesq]

Is there an existing issue for this?
Please search to see if an issue already exists for the bug you encountered.
No

Current Behavior
A concise description of what you're experiencing.
When we try to download a huge data-table in GeoJSON, the UI freeze ans sometime JSON.Stringnify fails as it is too big.
We need to process by chunk and use a WebWorker to encapsulate the geometry reprojection in the download.

Expected Behavior
A concise description of what you expected to happen.
The download should not freeze the UI and user should be informed of the progress by the snackbar

Steps To Reproduce
Steps to reproduce the behavior:

1. Go to https://canadian-geospatial-platform.github.io/geoview/public/outlier-ESRI-maxRecordCount.html or https://canadian-geospatial-platform.github.io/geoview/public/outlier-elections-2019.html
2. Click on Data-Table then click on election dataset
3. Click download as GeoJSON
4. See UI freeze and error for the election 2019 as dataset is too big for the stringnify

Anything else?
References? Anything that will give us more context about the issue you are encountering and if applicable, add screenshots to help explain your problem.