Custom filter table: Add ability to edit multiple filters in the custom filter table

User story

As a filter list author, it is important for me to be able to easily copy, add and remove multiple filters in the custom filter table so that I can directly edit my custom filter list quickly.

Background

Filter list authors need to be able to add and remove multiple filter rules within the custom filter table. Filter list authors often use an alternative text editor tool to create and edit filter rules, which they then copy and paste into the custom filter area, to test the filters live. The ability to copy, paste and delete multiple filters was a feature which existed in the legacy Firefox extension, and with the move away from a simple text box, to a table format, the table should be able to handle this function.

What to change

• Allow users to select multiple filters in the table
• Allow users to select and copy multiple filters in the table
• Allow users to paste multiple filter rules into the "search bar" and paste each filter rule into a separate row in the table
• Allow users to delete multiple filters in the table
• Spec update https://gitlab.com/eyeo/specs/spec/merge_requests/201