Add support for Asset ID matching

[domstubbs]

Description

This adds support for matching against Asset IDs (which are included in Craft content exports) instead of just filenames (which aren’t).

For simplicity I’ve just extended the existing jQuery logic for the settings form.

Related issues

#907
#597
#767

[terryupton]

Any update on this? @angrybrad @brandonkelly
I am facing the same issue.

I am trying to use Feedme in Craft 5 to import some existing craft data and move it from a matrix to section.
I am hitting an issue with the importing/assigning of images.
In my data a JSON file the image is stored as an ID:
"image": [
24922
]

In my feed me config I have assigned it as per screenshot.

However, when I run the import all the other data is mapped correct but the image/asset field is not no image is assigned.