use rollup to do bundle splitting

this uses dynamic imports for the cache provider and should thus solve the
deprecated import error when using warpbuild

src/restore.ts

@@ -12,7 +12,7 @@ process.on("uncaughtException", (e) => {
 });
 
 async function run() {
-  const cacheProvider = getCacheProvider();
+  const cacheProvider = await getCacheProvider();
 
   if (!cacheProvider.cache.isFeatureAvailable()) {
     setCacheHitOutput(false);
@@ -42,9 +42,10 @@ async function run() {
       lookupOnly,
     });
     if (restoreKey) {
-      const match = restoreKey.localeCompare(key, undefined, {
-	sensitivity: "accent"
-      }) === 0;
+      const match =
+        restoreKey.localeCompare(key, undefined, {
+          sensitivity: "accent",
+        }) === 0;
       core.info(`${lookupOnly ? "Found" : "Restored from"} cache key "${restoreKey}" full match: ${match}.`);
       if (!match) {
         // pre-clean the target directory on cache mismatch

src/save.ts

@@ -13,7 +13,7 @@ process.on("uncaughtException", (e) => {
 });
 
 async function run() {
-  const cacheProvider = getCacheProvider();
+  const cacheProvider = await getCacheProvider();
 
   const save = core.getInput("save-if").toLowerCase() || "true";
 

src/utils.ts

@@ -1,7 +1,5 @@
 import * as core from "@actions/core";
 import * as exec from "@actions/exec";
-import * as warpbuildCache from "@actions/warpbuild-cache";
-import * as ghCache from "@actions/cache";
 import fs from "fs";
 
 export function reportError(e: any) {
@@ -42,8 +40,8 @@ export async function getCmdOutput(cmdFormat: string, cmd: string, options: exec
 }
 
 export interface GhCache {
-  isFeatureAvailable: typeof ghCache.isFeatureAvailable;
-  restoreCache: typeof ghCache.restoreCache;
+  isFeatureAvailable: typeof import("@actions/cache").isFeatureAvailable;
+  restoreCache: typeof import("@actions/cache").restoreCache;
   saveCache: (paths: string[], key: string) => Promise<string | number>;
 }
 
@@ -52,15 +50,15 @@ export interface CacheProvider {
   cache: GhCache;
 }
 
-export function getCacheProvider(): CacheProvider {
+export async function getCacheProvider(): Promise<CacheProvider> {
   const cacheProvider = core.getInput("cache-provider");
   let cache: GhCache;
   switch (cacheProvider) {
     case "github":
-      cache = ghCache;
+      cache = await import("@actions/cache");
       break;
     case "warpbuild":
-      cache = warpbuildCache;
+      cache = await import("@actions/warpbuild-cache");
       break;
     default:
       throw new Error(`The \`cache-provider\` \`${cacheProvider}\` is not valid.`);