Add the possibility run shell scripts from filemanager on android (#6288)

frontend/device/android/device.lua

@@ -5,6 +5,7 @@ local ffi = require("ffi")
 local C = ffi.C
 local lfs = require("libs/libkoreader-lfs")
 local logger = require("logger")
+local util = require("util")
 local _ = require("gettext")
 local T = require("ffi/util").template
 
@@ -349,6 +350,13 @@ function Device:exit()
     android.lib.ANativeActivity_finish(android.app.activity)
 end
 
+function Device:canExecuteScript(file)
+    local file_ext = string.lower(util.getFileNameSuffix(file))
+    if android.prop.flavor ~= "fdroid" and file_ext == "sh"  then
+        return true
+    end
+end
+
 android.LOGI(string.format("Android %s - %s (API %d) - flavor: %s",
     android.prop.version, getCodename(), Device.firmware_rev, android.prop.flavor))