feat: Add cURL Import Option to Create Dropdown Menu

Problem

Users had to discover the cURL import feature by accident (pasting into URL bar or via Import Data dialog, atleast I discovered it by accident). This made it hard to find and use.

Solution

Added a dedicated "cURL" option to the Create dropdown (Cmd+N) that opens a professional dialog for importing cURL commands.

Created a Quick PR as well:

https://github.com/mountain-loop/yaak/pull/293