Add Option for uploading "excluded" folders

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### Feature description

I have a media folder. This media folder contains a lot of subfolders, most of them are not synced.
When i add a folder that is excluded, the log shows an entry that this folder has been excluded, and it's content therefore will not be synced.

I would like to see an option to the desktop client, so that a locally added, but excluded folder will then be "included" and synced automatically. Conflict resolution would then be applied like those files existed beforehand.