Core: Consolidate write.folder-storage.path and write.object-storage.path to write.data.path

[flyrain]

Per discussion in #2965, we deprecate both write.folder-storage.path and write.object-storage.path, and use write.data.path instead.

Created a new method LocationProviders::dataLocation to get the data location and to be compatible with deprecated configs.

cc @rdblue @jackye1995 @aokolnychyi @RussellSpitzer @kbendick @karuppayya