Introduce wrapper for codeql pack add CLI command

Similar to what we do with `codeql pack install`.

Tnis will simulate us running `codeql pack add codeql/<language>-all`.

We're going to need in order to:
- generate a lock file (codeql-pack.lock.yaml)
- install the correct packages for our skeleton QL pack based on the
lock file.

extensions/ql-vscode/src/cli.ts

@@ -28,6 +28,7 @@ import { CompilationMessage } from "./pure/legacy-messages";
 import { sarifParser } from "./sarif-parser";
 import { dbSchemeToLanguage, walkDirectory } from "./helpers";
 import { App } from "./common/app";
+import { QueryLanguage } from "./qlpack-generator";
 
 /**
  * The version of the SARIF format that we are using.
@@ -1216,6 +1217,23 @@ export class CodeQLCliServer implements Disposable {
     );
   }
 
+  /**
+   * Adds a list of QL library packs with optional version ranges as dependencies of
+   * the current package, and then installs them. This command modifies the qlpack.yml
+   * file of the current package. Formatting and comments will be removed.
+   * @param dir The directory where QL pack exists.
+   * @param language The language of the QL pack.
+   */
+  async packAdd(dir: string, queryLanguage: QueryLanguage) {
+    const args = ["--dir", dir];
+    args.push(`codeql/${queryLanguage}-all`);
+    return this.runJsonCodeQlCliCommandWithAuthentication(
+      ["pack", "add"],
+      args,
+      "Adding pack dependencies and installing them",
+    );
+  }
+
   /**
    * Downloads a specified pack.
    * @param packs The `<package-scope/name[@version]>` of the packs to download.