NetDb: Update Handling of Local Lease Sets.

With the introduction of segmented netDb, the handling of
local LeaseSets has changed substantially, based on the role
being assumed.
Role #1) The 'floodfill' netDb when the router is a FloodFill
         In this case, the router would actually de-anonymize
         the clients it is hosting if it refuses LeaseSets for
         these clients.
         The LS will be checked to make sure it arrived directly,
         and handled as a normal LS.
Role #2) The 'floodfill' netDb when the router is *NOT* an I2P
         network Floodfill.
         In this case, the 'floodfill' netDb only stores RouterInfo.
         There is no use case for the 'floodfill' netDb to store any
         LeaseSets when the router is not a FloodFill.
Role #3) Client netDb should only receive LeaseSets from their
         tunnels.  And clients will only publish their LeaseSet
         out their client tunnel.
         In this role, the only LeaseSet that should be rejected
         is its own LeaseSet.

         ToDo: Currently, the 'floodfill' netDb will be excluded
         from directly receiving a client LeaseSet, due to the
         way the selection of FloodFill routers are selected
         when flooding a LS.
         But even if the host router does not directly receive the
         LeaseSets of the clients it hosts, those LeaseSets will
         usually be flooded back to it.
         Is this enough, or do we need to pierce the segmentation
         under certain conditions?

         ToDo: What considerations are needed for multihoming?
         with multihoming, it's really important to prevent the
         client netDb from storing the other guy's LeaseSet.
         It will confuse us badly.

Signed-off-by: obscuratus <obscuratus@mail.i2p>