Add means to specify sqlite db file path for tapd test harness and db unit tests #2004

Job	Run time
Compilation check	29s
cross compilation	8m 26s
Format check	15s
Docker build check	2m 46s
run itests	8m 45s
run itests postgres	14m 5s
Lint check	1m 52s
go mod check	25s
RPC check	58s
Sqlc check	24s
test vector check	1m 4s
run unit tests (unit-race)	4m 58s
run unit tests (unit-cover)	2m 44s
run unit tests (unit dbbackend=postgres)	3m 40s
	50m 51s

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