feat(datatable): add remove column method

[TomJGooding]

Description

Add a remove_column method to remove individual columns from a DataTable. The code is essentially just a copy of the existing remove_row method, apart from deleting from DataTable._data.

Related Issue

• How to remove a column from a DataTable? #2897

How Has This Been Tested?

The new test simply checks the column length and the row data after a column is removed. This has also been tested manually with a simple app that removes the column under the cursor (as described in the updated docs).

There are currently no snapshot tests. If this is required I'm afraid I may need some guidance!

Checklist:

• Docstrings on all new or modified functions / classes
• Updated documentation
• Updated CHANGELOG.md (where appropriate)

[TomJGooding]

P.S. I found it a bit difficult to understand the existing remove method through all the red mist in my editor, as mypy really isn't happy! I haven't delved into the code yet but I wonder if this could be improved?

[darrenburns]

Looks good, thanks!

[willmcgugan]

Thanks, Tom!