Fix file name generation for uploaded images

[rdy4ever]

Questions	Answers
Description?	In the latest version of the module, newly uploaded slides (for example, after upgrade) have wrong file names (double extension concatenated in the name and no dot to separate it - for example: 48fef018a667ee0b10f9d4da0c619f8186a00f5test_namejpgjpg). This PR fixes the file name generation.
Type?	bug fix
BC breaks?	no
Deprecations?	no
Fixed ticket?	Fixes #119
How to test?	Upload new images and see that now the file names are correct

[ps-jarvis]

Hello @rdy4ever!

This is your first pull request on ps_imageslider repository of the PrestaShop project.

Thank you, and welcome to this Open Source community!

[boo-code]

QA — verified ✅

Reproduced the filename generation on ps_imageslider.php and confirmed the fix, using Tools::str2url/pathinfo exactly as on the touched line:

input filename	before	after (this PR)
My Test.JPG	my-testjpgjpg	my-test.jpg

Before, str2url($name) . $type stripped the dot out of the original name and then concatenated the extension again, producing a double, dotless extension. pathinfo($name, PATHINFO_FILENAME) drops the original extension first, and the explicit '.' restores the separator, so the result is a single, correct name.ext.

This also resolves #126 (same line, "saved without a dot/extension") — they're the same bug, so #126 can be closed as a duplicate of #119 once this is merged. LGTM.