Allow different names for ...rest (#3954)

* Allow different names for ...rest

* Resolves #3945

* This change requires an explicit name for the rest argument in `WholeStreamCommand`,
  which is why there are so many changed files.

* Remove redundant clone

* Add tests

crates/nu-command/src/commands/filesystem/mkdir.rs

@@ -12,6 +12,7 @@ impl WholeStreamCommand for Mkdir {
     fn signature(&self) -> Signature {
         Signature::build("mkdir")
             .rest(
+                "rest",
                 SyntaxShape::FilePath,
                 "the name(s) of the path(s) to create",
             )

crates/nu-command/src/commands/filesystem/rm.rs

@@ -26,7 +26,11 @@ impl WholeStreamCommand for Remove {
             )
             .switch("recursive", "delete subdirectories recursively", Some('r'))
             .switch("force", "suppress error when no file", Some('f'))
-            .rest(SyntaxShape::GlobPattern, "the file path(s) to remove")
+            .rest(
+                "rest",
+                SyntaxShape::GlobPattern,
+                "the file path(s) to remove",
+            )
     }
 
     fn usage(&self) -> &str {

crates/nu-command/src/commands/filesystem/touch.rs

@@ -19,7 +19,7 @@ impl WholeStreamCommand for Touch {
                 SyntaxShape::FilePath,
                 "the path of the file you want to create",
             )
-            .rest(SyntaxShape::FilePath, "additional files to create")
+            .rest("rest", SyntaxShape::FilePath, "additional files to create")
     }
     fn usage(&self) -> &str {
         "Creates one or more files."