jsonrpc-server: Separate changing read_only status from reconnecting.

jsonrpc-server: Separate changing read_only status from reconnecting.

The code in jsonrpc-server conflated two different kinds of functionality.
It makes sense for the client to be able to change whether a particular
server is read-only.  It also makes sense for the client to tell a server
to reconnect.  The code in jsonrpc-server only provided a single function
that does both, which is weird.  This commit breaks these apart.

Signed-off-by: Ben Pfaff <blp@ovn.org>
Acked-by: Justin Pettit <jpettit@ovn.org>