Option to bypass "getOne" step

[coudot]

For small directories, or when few attributes are synced, we could fetch all values in the "getAll" step and bypass the "getOne" step for each entry in source.

[coudot]

This issue was about improving performances on source (requesting all entries at once) but we could also try the same thing with the destination: use the getAll request to load all data in memory instead of requesting each entry. This would be a major improvement for plugins using REST API in destination.