Add new packs input to init action

This input allows users to specify which packs to run. It works in
unison with the packs block of the config file and it is similar to
how `queries` works. They both use `+` in the same way.

Note that the `#TODO` in the pr check is still around, but the CLI
is available. I will remove the TODO in the next commit.

src/init-action.ts

@@ -153,6 +153,7 @@ async function run() {
     config = await initConfig(
       getOptionalInput("languages"),
       getOptionalInput("queries"),
+      getOptionalInput("packs"),
       getOptionalInput("config-file"),
       getOptionalInput("db-location"),
       parseRepositoryNwo(getRequiredEnvParam("GITHUB_REPOSITORY")),