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/runner.js

@@ -137,6 +137,7 @@ program
             externalRepoAuth: auth,
             url: (0, util_1.parseGitHubUrl)(cmd.githubUrl),
             apiURL: undefined,
+            registriesAuthTokens: undefined,
         };
         const gitHubVersion = await (0, util_1.getGitHubVersion)(apiDetails);
         (0, util_1.checkGitHubVersionInRange)(gitHubVersion, logger, util_1.Mode.runner);
@@ -279,6 +280,7 @@ program
             auth,
             url: (0, util_1.parseGitHubUrl)(cmd.githubUrl),
             apiURL: undefined,
+            registriesAuthTokens: undefined,
         };
         const outputDir = cmd.outputDir || path.join(config.tempDir, "codeql-sarif");
         let initEnv = {};
@@ -325,6 +327,7 @@ program
         auth,
         url: (0, util_1.parseGitHubUrl)(cmd.githubUrl),
         apiURL: undefined,
+        registriesAuthTokens: undefined,
     };
     try {
         const gitHubVersion = await (0, util_1.getGitHubVersion)(apiDetails);