Implement grouping for Text types.

[kgodey]

Problem

Users may want to group records that contain Text types by first word or first character of the text value.

We need to provide the ability to group by these.

Solution

We should extend our record grouping mechanism to accept first word or first character as grouping parameters for columns of Text types

This involves:

• Implementing the grouping in the backend
• Updating the /api/v0/databases/<id>/types/ endpoint to store available grouping on this type This will be done in Grouping description endpoint #1310

Additional context

• Please see these PRs for code related to grouping:
  • Record grouping #315
  • Fix grouping counts #353
• Complete implementation of this issue is blocked by implementation of Text types, but we can start work with the VARCHAR type which is already implemented.
  • Handle VARCHAR data type in the backend. #404
  • Handle TEXT data type in the backend. #405
  • Handle CHAR data type in the backend. #407
• Update filtering issues to cover storing filter/group information in the backend. #557 provides some context on storing groups.