tchrpc: change FundChannel endpoint to POST #3493

Job	Run time
Docker build check	3m 36s
cross compilation	11m 51s
Format check	21s
Compilation check	1m 34s
run itests	10m 49s
run itests postgres	18m 51s
Lint check	2m 38s
migration version check	8s
go mod check	24s
RPC check	1m 9s
run LiT tests	6m 3s
sample configuration check	38s
Sqlc check	2m 50s
test vector check	53s
run unit tests (unit-race)	11m 37s
run unit tests (unit-cover)	4m 23s
run unit tests (unit dbbackend=postgres)	5m 45s
finish	3s
	1h 23m 33s

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