Run Dialog Attempts to Execute Escaped File/Directory Paths

 * Cinnamon version: 5.0.7
 * Distribution: Linux Mint 20.2 Uma
 * Graphics Hardware: GeForce GTX 1050 Ti
 * Graphics Driver: nvidia-driver-470 / 470.86-0ubuntu0.20.04.1
 * System Architecture: x86_64

Issue
When using the Run Dialog, tab completion will automatically escape spaces. This is problematic in some cases.

When running a command on a file from the Run Dialog, this is fine, however, when entering just a file/directory path into the Run Dialog, the run dialog allows you to quickly open that path... but if you tab complete, it will escape the spaces, which the Run Dialog will then attempt to execute as a program rather than opening with an appropriate associated program or prompting for the selection of one.

The following is an example where attempting to open a particular folder under ~/Pictures containing a space where tab completion was used.

Steps to reproduce

1. Pull up Run Dialog
2. Tab Complete a path containing a space
3. Press The Enter Key

Expected behaviour
If the file is not an executable program with the executable permission, it should instead open with its associated program, such as Nemo or Xed or prompt the user to select an appropriate application.

Cinnamon's Run Dialog can open files with non-escaped spaces normally and should not treat non-executable file paths with escaped spaces differently, especially since it will escape spaces on its own with the tab completion.

Start with the Cinnamon Run Dialog entry point and reproduce the issue by tab-completing a path containing spaces, then pressing Enter. Trace how escaped paths are classified and launched. Done means a non-executable file or directory with escaped spaces opens with its associated application or prompts for an application instead of being executed.