Implement setting a column as non-nullable or unique

[kgodey]

Problem

Users might want to set a column to not allow empty values or not allow duplicates.

Proposed solution

The "Working with Columns" design spec has a solution for this, which we need to implement on the frontend.

Sub-tasks:

• Add "Allow NULL" toggle option to column header menu #771
• Add "Allow Duplicates" toggle option to column header menu #772
• Add UI to filter on the presence of duplicate values in one column #770

Related but moved to a later milestone:

• Improve UX when adding new records to a table with a NOT NULL column #775
• Add UI to filter on a value being NULL #789
• Prompt user to add a filter that displays problematic values when it's not possible to set a column constraint #773

Additional context

• Backend work:
  • Create a Column API #199 for not-null
  • CRUD API for table constraints #326 for unique
  • Allow filtering in record list API #157 for filtering by not-null
  • Add filter to show records with duplicate values in a set of columns #501 for filtering by unique
• Design issue: Design for editing column properties and table constraints #324
• Design discussion: Working with Columns #436
• Mapping DB data types to Mathesar data types #269