shell: expand ~ in local file path arguments (#9265)

* shell: expand `~` in local file path arguments

The weed shell parses commands itself instead of going through an OS
shell, so a path like `~/Downloads/foo.meta` was passed verbatim to
`os.Open`, which fails because no `~` directory exists. Users had to
spell out absolute home paths in every command.

Add an `expandHomeDir` helper that resolves a leading `~` or `~/...` to
the user's home directory, and run user-supplied local file paths in
the affected shell commands through it:

  fs.meta.load          (positional file)
  fs.meta.save          (-o)
  fs.meta.changeVolumeId (-mapping)
  s3.iam.export         (-file)
  s3.iam.import         (-file)
  s3.policy             (-file)
  s3tables.bucket       (-file)
  s3tables.table        (-file, -metadata)
  volume.fsck           (-tempPath)

Filer-namespace path flags (`-dir`, `-path`, `-locationPrefix`, etc.)
are unaffected; they live in the filer, not on the local FS.

* shell: reuse util.ResolvePath instead of a new helper

util.ResolvePath already does tilde expansion; drop the local
expandHomeDir helper and route every shell call site through it.

weed/shell/command_s3_iam_export.go

@@ -11,6 +11,7 @@ import (
 	"github.com/seaweedfs/seaweedfs/weed/filer"
 	"github.com/seaweedfs/seaweedfs/weed/pb"
 	"github.com/seaweedfs/seaweedfs/weed/pb/iam_pb"
+	"github.com/seaweedfs/seaweedfs/weed/util"
 	"google.golang.org/grpc"
 )
 
@@ -58,8 +59,9 @@ func (c *commandS3IAMExport) Do(args []string, commandEnv *CommandEnv, writer io
 		}
 
 		var out io.Writer = writer
-		if *file != "" {
-			fp, err := os.OpenFile(*file, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
+		outputFile := util.ResolvePath(*file)
+		if outputFile != "" {
+			fp, err := os.OpenFile(outputFile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
 			if err != nil {
 				return fmt.Errorf("create file: %v", err)
 			}
@@ -72,8 +74,8 @@ func (c *commandS3IAMExport) Do(args []string, commandEnv *CommandEnv, writer io
 		}
 		fmt.Fprintln(out)
 
-		if *file != "" {
-			fmt.Fprintf(writer, "Exported IAM configuration to %s\n", *file)
+		if outputFile != "" {
+			fmt.Fprintf(writer, "Exported IAM configuration to %s\n", outputFile)
 		}
 		return nil
 	}, commandEnv.option.FilerAddress.ToGrpcAddress(), false, commandEnv.option.GrpcDialOption)