Allow running shell scripts from the FileManager/Favorites (#5804)

* Allow running Shell/Python scripts from the FM

* Show an InfoMessage before/after running the script

Since we're blocking the UI ;).

* Allow running scripts from the favorites menu, too.

frontend/util.lua

@@ -661,6 +661,33 @@ function util.getFileNameSuffix(file)
     return suffix
 end
 
+--- Returns true if the file is a script we allow running
+--- Basically a helper method to check a specific list of file extensions.
+---- @string filename
+---- @treturn boolean
+function util.isAllowedScript(file)
+    local file_ext = string.lower(util.getFileNameSuffix(file))
+    if file_ext == "sh"
+    or file_ext == "py" then
+        return true
+    else
+        return false
+    end
+end
+
+--- Companion helper function that returns the script's language,
+--- based on the filme extension.
+---- @string filename
+---- @treturn string (lowercase) (or nil if !isAllowedScript)
+function util.getScriptType(file)
+    local file_ext = string.lower(util.getFileNameSuffix(file))
+    if file_ext == "sh" then
+        return "shell"
+    elseif file_ext == "py" then
+        return "python"
+    end
+end
+
 --- Gets human friendly size as string
 ---- @int size (bytes)
 ---- @bool right_align (by padding with spaces on the left)