upload_and_run doesn't separate $command from first arg

Describe the bug

When doing this:

my $output = upload_and_run <<~'BASH', 'foo';
#!/bin/bash
echo $1
BASH

...this produces an error, because it's trying to execute /tmp/${random_string}.tmpfoo on the server (observe that there's no space separating the command from the first argument).

Expected behavior

$output should equal the string foo

How to reproduce it

Write the code in the bug description inside a task, and see the error being output.

Code example

No response

Additional context

No response

Rex version

1.14.3

Perl version

v5.38.2

Operating system running rex

Void Linux

Operating system managed by rex

Debian

How rex was installed?

package manager

Start by locating the upload_and_run implementation and the code that assembles the remote command and its first argument. Reproduce the task from the issue on Rex 1.14.3, then verify that the command is separated correctly and the example returns the string "foo".