Allow user to remove a foreign key constraint from the column header menu

[seancolsen]

Current behavior

• To remove a FK constraint, the user must open the Table Constraints dialog.

Desired behavior

• Find a column associated with a single-column foreign key constraint.
• Click on the column header to open the column header menu.
• Choose "Remove Table Link".
• Observe the same loading/success/error behavior as when clicking on the "Allow NULL" option in the column header menu.

Limitations

• To delete a multi-column foreign key, you'll still need to do it from the Table Constraints dialog.

Additional context

• Foreign Key Constraints Spec -- see Scenario 2.

[seancolsen]

@kgodey I put this in the same milestone as all the other FK tickets, but I think we could safely defer it until later. I'll leave it to you to re-prioritize if you so choose.

[kgodey]

@kgodey I put this in the same milestone as all the other FK tickets, but I think we could safely defer it until later. I'll leave it to you to re-prioritize if you so choose.

I think it's important to do this with the rest of the feature to make it friendlier for non-technical users. It seems like it would be pretty quick to implement.