Deprecate farm_log_asset_names_summary()

Problem/Motivation

See the original pull request for more context: https://github.com/farmOS/farmOS/pull/671

The farm_log_asset_names_summary() function was added to accommodate two needs during the upgrade from farmOS 1.x to 2.x: the "Move assets" and "Group assets" bulk actions.

Proposed resolution

I'd like to suggest that we refactor those two actions into quick forms, which are prepopulated from the actions. Then the logic within farm_log_asset_names_summary() can become a helper method within QuickStringTrait. This serves to further encapsulate helper functions like this into quick form traits.

Those can be separate issues. This issue is JUST to deprecate farm_log_asset_names_summary().

User interface changes

None.

API changes

farm_log_asset_names_summary() will be deprecated in farmOS 2.x and removed from farmOS 3.x.

Data model changes

None.