[FAB-11780] added membership provider to ledger

had to refactor a bit, as membership provider creation was
dependant on collectionStore, which is created per channel,
therefore membership provider was also created per channel.

changed it such that we can create a single membership provider

FAB-11780 - #done

Change-Id: I2c44ebf00d6eea1fc1d713b3168328f95074c6b5
Signed-off-by: nirro <nirro@il.ibm.com>