Show RPC calls from config in lock monitor

With this patch all RPC calls at runtime of masterd will show up in the
lock monitor. There is a chicken-and-egg issue with initializing the
configuration with a context since the lock manager, containing the
monitor, requires the configuration. This is worked around by setting
the config's context only once the lock monitor is available.

Example:
rpc/node19.example.com/write_ssconf_files  Jq9/Job32/N_SET_PARAMjobqueue_update  Jq2/Job27/C_VERIFY_CONFIG

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>