Fix volume.fsck -forcePurging -reallyDeleteFromVolume to fail fast on filer traversal errors (#8015)

* Add TraverseBfsWithContext and fix race conditions in error handling

- Add TraverseBfsWithContext function to support context cancellation
- Fix race condition in doTraverseBfsAndSaving using atomic.Bool and sync.Once
- Improve error handling with fail-fast behavior and proper error propagation
- Update command_volume_fsck to use error-returning saveFn callback
- Enhance error messages in readFilerFileIdFile with detailed context

* refactoring

* fix error format

* atomic

* filer_pb: make enqueue return void

* shell: simplify fs.meta.save error handling

* filer_pb: handle enqueue return value

* Revert "atomic"

This reverts commit 712648bc354b186d6654fdb8a46fd4848fdc4e00.

* shell: refine fs.meta.save logic

---------

Co-authored-by: Chris Lu <chris.lu@gmail.com>

weed/shell/command_fs_verify.go

@@ -300,7 +300,7 @@ func (c *commandFsVerify) verifyTraverseBfs(path string) (fileCount uint64, errC
 			}
 			return nil
 		},
-		func(outputChan chan interface{}) {
+		func(outputChan chan interface{}) error {
 			var wg sync.WaitGroup
 			itemErrCount := atomic.NewUint64(0)
 			for itemEntry := range outputChan {
@@ -315,5 +315,6 @@ func (c *commandFsVerify) verifyTraverseBfs(path string) (fileCount uint64, errC
 			}
 			wg.Wait()
 			errCount = itemErrCount.Load()
+			return nil
 		})
 }