Add the option to select which pending uploads to upload

[ciupava]

Title sounds a bit odd, let me try to explain: currently the Configuration/Pending uploads tab allows you to either delete the change one by one, or upload them all in bulk.
Suppose that, while on the field, you have added a POI which you would like to edit later on to integrate more info(maybe you are in a rush, or would like to check further sources, but you have at least the correct position, which you want to keep), and at the same time added some POI which you are happy to upload already. In this type of situation, it would be great to have the option to choose which changes to upload, one by one, like you can do for the deletion.
Would it be too hard to implement @Zverik?
Maybe touching on issues #368 and #601.
Thanks for this great app!