CSV file export size estimate and disk space protection

[elehmer]

Description of PR

This PR adds a CSV file size estimate and helps protect file system from filling up. The file estimate is just a 1st approximation using 150 characters per line as a guess. It also removes the 0.85GB CSV file limit (let users decide if the file is too big for their use). We still warn of larger than Excel can handle and warning that large CSV export will take awhile.

Summary of changes and related issue

https://trello.com/c/5J8YQ2HI/569-ability-to-estimate-manage-file-sizes-csv

Relevant motivation and context

Protect HUB file system from filling up from CSV export.

Dependencies required for this change?

Fixes # (issue), delete if not necessary

Type of change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ x ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce.

• [ x ] Tested on HUB for various sized CSV exports

Checklist:

• [ x ] My code follows the style guidelines of this project
• [ x ] I have performed a self-review of my code
• [ x ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ x ] My changes generate no new warnings
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ x ] New and existing unit tests pass locally with my changes
• [ ] Any dependent changes have been merged and published in downstream modules

[mdkoenig]

Ability to ~estimate~ manage file sizes (CSV)

[claalmve]

Looks good to me! I tested on NetCDF and CSV exports of data and they all work well. Warnings are definitely helpful for users to consider subsetting datasets before exporting.

I made a couple comments but nothing critical.