Implement rpc timeout annotation

[DivineThreepwood]

An additional rpc annotation would be nice to configure individual timeouts of rpc methods.
Since the default timeout is 1 minute, some more heavy computations take maybe some more time which should be individually configurable.

• implement annotation
• handle individual timeouts within the rpc helper

Currently the default rpc timeout is set to 5 min. which should be reduced back to one minute after this feature is implemented. Additionally the rpc timeout of all bco registry rpcs needs to be increased back to 5 min.