[Image save] Change files in filesystem before store to DB

[Elfangor93]

This PR applies one possible solution to solve the issue reported in #341.

All changes in the file and folders are processed before the item gets stored to the database. If an error appears while changing things in the filesystem, the item will not be stored and the save process is cancelled.

How to test this PR

Create, Edit, Delete, Move, Rename Images and Categories.
Everything should work as before.
Optional: Check that Database and Folderstructure are consistent.

[MrMusic]

I noticed the following problem during testing: Moving images to another category is not possible if no original image file is available.

1. switching off creating 'original' images in the JG configuration
2. uploading images
3. attempts to move an image to another category
4. error message: “Save failed with the following error: ”
5. But detail image and thumbnail have been moved to the other folder

[MrMusic]

Unable to change an image alias.
If you try to change the alias of a saved image, the following error message appears:
Save failed with the following error:
For categories, the alias can be changed without any problems.

[Elfangor93]

Unable to change an image alias.

I can not reproduce this issue. Changing the alias is perfectly possible.

[MrMusic]

I can not reproduce this issue. Changing the alias is perfectly possible.

It depends on what is set in the JoomGallery configuration for use 'Original filename'.

1. Set 'Original filename' to Yes in the JG configuration
2. Uploading images
3. Attempts to change an image alias
   Error message: "Save failed with the following error: "
   ->New alias cannot be saved

[Elfangor93]

Unable to change an image alias.

@MrMusic Is fixed now.

[MrMusic]

@MrMusic Is fixed now.

Thanks.

I have tested this PR ✅ successfully.
Thank you very much!