rpc: add SetPendingTransferProofCourierAddr endpoint to fix erroneous courier addresses #3094

Job	Run time
Docker build check	3m 32s
cross compilation	10m 38s
Compilation check	1m 2s
Format check	24s
run itests	9m 30s
run itests postgres	17m 41s
Lint check	2m 39s
migration version check	21s
go mod check	23s
RPC check	1m 39s
sample configuration check	41s
Sqlc check	2m 44s
test vector check	55s
run unit tests (unit-race)	6m 44s
run unit tests (unit-cover)	3m 45s
run unit tests (unit dbbackend=postgres)	4m 56s
finish	5s
	1h 7m 39s

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