[G2M] Column aliases - Githubissues

Closes #212

Changes:

added a centralized dev-only Column Alias Configuration in the left panel to be able to add aliases for all columns in one place
this would be particular useful when deciding to export all widget data to a CSV file and we need to change several column names in the same time
the aliases changed in this feature are not instantaneously updated in the widget state until the Submitted button is pressed. We might change this feature in the future, but only after the formatted column names / aliases are not added to the data objects while changes are taking place, which is the way the process works at the moment
the feature has validation implemented: if one column key is associated with an existing alias an error message will appear under the affected aliases and the Submit button will be disabled

Other changes:

because the panels on the right & left are really long at the moment, I changed the styling for the central Widget to be sticky and not extend vertically beyond the screen extent.

Recording:

To test:

EQWorks / widget-studio