Improve link row field copy/paste and import

This merge request introduce the ability to give text values to single_select, multiple_select and link_row fields so that you don't have to know the ids of the related select options/rows to import or paste textual data.

For now only linked single value primary field table can be imported this way which means it excludes a linked table with multiple_select, file_field, collaborator_field and link_row field as primary field.

If there is an ambiguity: two options with the same name or two rows that match the same value, the first one in their ordering is used.

The main visible difference from a end user perspective is that you can now import a table with linked rows and you can paste text values to link row field.

I've also simplified a bit the maintenance by using the prepare_value_for_db_in_bulk method even for one value.

To test the feature,

1. populate the test data (you might need to drop the exiting test database first) and export the table in CSV then reimport it.
2. copy a link row field value, paste it in a text file (this step is crucial otherwise your are in rich copy/paste mode) then copy/paste it in a link row field that contains the same textual values for various primary field linked table. (you can directly forge the values in your text editor also if you want to).
3. You can also use the API to create a new row with mixed id/text value for these fields.

Merge Request Checklist

• changelog.md has been updated if required
• New/updated Premium features are separated correctly in the premium folder
• The latest Chrome and Firefox have been used to test any new frontend features
• Documentation has been updated
• Quality Standards are met
• Performance: tables are still fast with 100k+ rows, 100+ field tables
• The redoc API pages have been updated for any REST API changes
• Our custom API docs are updated for changes to endpoints accessed via api tokens
• The UI/UX has been updated following UI Style Guide

Closes #1121 (closed)