Move some Actions related functions from routers to services (#33280)

Move the main logic of `generateTaskContext` and `findTaskNeeds` to the
`services` layer.

This is a part of #32751, since we need the git context and `needs` to
parse the concurrency expressions.

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

services/actions/init_test.go

@@ -17,9 +17,7 @@ import (
 )
 
 func TestMain(m *testing.M) {
-	unittest.MainTest(m, &unittest.TestOptions{
-		FixtureFiles: []string{"action_runner_token.yml"},
-	})
+	unittest.MainTest(m)
 	os.Exit(m.Run())
 }