test: add tests for capture command

Signed-off-by: Alessio Greggi <[email protected]>

tests/integration.txtar

@@ -27,7 +27,7 @@ cmp profile.json expected-profile.json
 
 # test harpoon capture command
 exec harpoon capture -h
-stderr 'harpoon capture [flags]'
+stdout 'Usage:'
 
 exec harpoon capture -f main.main -c -- ./bin/example-app coin
 stdout 'stdout: [flip coin]'