support dropping files into code field to insert `import("path")`

[WebFreak001]

New since https://code.visualstudio.com/updates/v1_70#_drop-into-editor-api

When dropping in files from a stringImportPaths folder, we could resolve the path to import the file and write down import("...") into the code.

Not sure yet about alternative functionality and what the default non-modified behavior is.