Add support for downloading packs from GHES

This change adds:

- new `registries` block allowed in code scanning config file
- new `registries-auth-tokens` input in init action
- Change the downloadPacks function so that it accepts new parameters:
    - registries block
    - api auth
- Generate a qlconfig.yml file with the registries block if one is
  supplied. Use this file when downloading packs.
- temporarily set the `GITHUB_TOKEN` and `CODEQL_REGISTRIES_AUTH` based
  on api auth

TODO:

1. integration test
2. handle pack downloads when the config is generated by the CLI

lib/api-client.js

@@ -65,6 +65,8 @@ function getApiDetails() {
         auth: (0, actions_util_1.getRequiredInput)("token"),
         url: (0, util_1.getRequiredEnvParam)("GITHUB_SERVER_URL"),
         apiURL: (0, util_1.getRequiredEnvParam)("GITHUB_API_URL"),
+        // only available in the init action
+        registriesAuthTokens: (0, actions_util_1.getOptionalInput)("registries-auth-tokens"),
     };
 }
 // Temporary function to aid in the transition to running on and off of github actions.