1.dispatch队列时，只下发progress状态的请求

2.filecache trim时，在主线程中不读取文件，减少主线程逻辑开销

Signed-off-by: madixin <madixin@huawei.com>

library/src/main/ets/ImageKnifeDispatcher.ets

@@ -201,9 +201,15 @@ export class ImageKnifeDispatcher {
   }
 
   dispatchNextJob() {
-    let request = this.jobQueue.pop()
-    if (request !== undefined) {
-      this.executeJob(request)
+    while (true) {
+      let request = this.jobQueue.pop()
+      if (request === undefined){
+        break// 队列已无任务
+      }
+      else if (request.requestState === ImageKnifeRequestState.PROGRESS) {
+        this.executeJob(request)
+        break
+      }
     }
   }
 

library/src/main/ets/utils/FileCache.ets

@@ -204,10 +204,10 @@ export class FileCache {
         break
       }
       let delkey = this.lruCache.keys()[0]
-      let data: ArrayBuffer | undefined = FileUtils.getInstance().readFileSync(this.path + delkey)
-      if (data !== undefined) {
+      let remove: number | undefined = this.lruCache.remove(this.lruCache.keys()[0])
+      if (remove !== undefined) {
         FileUtils.getInstance().deleteFile(this.path + delkey)
-        this.removeMemorySize(data)
+        this.removeMemorySize(remove)
       }
       this.lruCache.remove(delkey)
     }