share/eds: configurable requesting mode for Retriever

Rn, Retriever reconstructs EDS quadrant-by-quadrant with the timeout based on blockTime. With the current state of the protocol, where we have ShrexEds as the main block requesting protocol and Retriever only as a fallback, requesting quadrant-by-quadrant has little value and only slows things down. Instead, we should introduce retrieval mode with two modes currently:
* `QuadrantMode` - current quadrant-by-quadrant retrieval)
* `FullBodyMode` - request everything at once(better name wanted) - new default