Add logic for modules caching

Such files as cache-restore.ts, cache-utils.ts, constants.ts,
cache-save.ts we added. Main.ts file now incorporates logic for using
files mentioned above.

src/cache-save.ts

@@ -0,0 +1,60 @@
+import * as core from '@actions/core';
+import * as cache from '@actions/cache';
+import fs from 'fs';
+import {State} from './constants';
+import {getCacheDirectoryPath, getPackageManagerInfo} from './cache-utils';
+
+// Catch and log any unhandled exceptions.  These exceptions can leak out of the uploadChunk method in
+// @actions/toolkit when a failed upload closes the file descriptor causing any in-process reads to
+// throw an uncaught exception.  Instead of failing this action, just warn.
+process.on('uncaughtException', e => {
+  const warningPrefix = '[warning]';
+  core.info(`${warningPrefix}${e.message}`);
+});
+
+export async function run() {
+  try {
+    await cachePackages();
+  } catch (error) {
+    core.setFailed(error.message);
+  }
+}
+
+const cachePackages = async () => {
+  const state = core.getState(State.CacheMatchedKey);
+  const primaryKey = core.getState(State.CachePrimaryKey);
+
+  const packageManagerInfo = await getPackageManagerInfo();
+  
+  const cachePath = await getCacheDirectoryPath(
+    packageManagerInfo,
+  );
+
+  if (!fs.existsSync(cachePath)) {
+    throw new Error(
+      `Cache folder path is retrieved but doesn't exist on disk: ${cachePath}`
+    );
+  }
+
+  if (primaryKey === state) {
+    core.info(
+      `Cache hit occurred on the primary key ${primaryKey}, not saving cache.`
+    );
+    return;
+  }
+
+  try {
+    await cache.saveCache([cachePath], primaryKey);
+    core.info(`Cache saved with the key: ${primaryKey}`);
+  } catch (error) {
+    if (error.name === cache.ValidationError.name) {
+      throw error;
+    } else if (error.name === cache.ReserveCacheError.name) {
+      core.info(error.message);
+    } else {
+      core.warning(`${error.message}`);
+    }
+  }
+};
+
+run();