Allow pack specifiers to include paths

Also, this cleans up our pack-related integration tests.
We are now testing with the most recent CLIs.

lib/codeql.js

@@ -642,7 +642,7 @@ async function getCodeQLForCmd(cmd, checkVersion) {
                 "download",
                 "--format=json",
                 ...getExtraOptionsFromEnv(["pack", "download"]),
-                ...packs.map(packWithVersionToString),
+                ...packs,
             ];
             const output = await runTool(cmd, codeqlArgs);
             try {
@@ -698,9 +698,6 @@ async function getCodeQLForCmd(cmd, checkVersion) {
     }
     return codeql;
 }
-function packWithVersionToString(pack) {
-    return pack.version ? `${pack.packName}@${pack.version}` : pack.packName;
-}
 /**
  * Gets the options for `path` of `options` as an array of extra option strings.
  */