Implement the new preliminary specification chages in OSGI SCR

[laeubi]

The Felix SCR implementation needs to be enhanced to support the new proposed specification change here:

• [ds] Add new component retention policy to control service lifecycle osgi/osgi#875

Originally described here

• [ds] support a retention policy for components osgi/osgi#720

in a previous discussion it was stated that apache felix maybe already contains such custom extension, we should check if this is the case and then reuse that as it now becomes specification compliant,