QTiledDataSource should be the gatekeeper of Tiled data

[padraic-shafer]

QTiledWidget and QTiledDataSource each have their own Tiled client object at the moment. This can lead to node paths and selections being out of sync (or needing sync mechanisms) with each other.

It would be cleaner for QTiledWidget to rely on QTiledDataSource as the state keeper and fetcher of data for the tiled client. Essentially let QTiledDataSource be the data source manager.

[AbbyGi]

Update:
Right now, the TiledDataSource, TiledRunSelector, and TiledCatalogSelector all connect to their own tiled client object through from_uri and store them as their own self.client attribute.

The TiledDataSource should be the only one connecting to the tiled client through from_uri and both the RunSelector and CatalogSelector should get Tiled info from the TiledDataSource.