Sensible download name

[abhaysp95]

This PR is meant for review purpose only as it's not complete yet

Feature Description

Allow user to toggle the setting to download the file with sensible file name.

What's the problem

NOTE: I'm taking the image as example for downloadable media for now

Previously the downloaded files where stored with the format subredditname + id, which in some cases (mentioned down below), didn't make much sense (visible in below image)

What's the fix

Provide user with toggle to enable this feature

Now, the downloaded files are provided with the post title too

Why is the feature necessary

• You want to search some downloaded media in your heap of already downloaded media in your storage. It will be easy if user can find the files by just typing some letter/words in filter of their file explorer/gallery
• Can write some scripts/tools to re-organize the downloaded media on the basis of the names by applying different sort of grouping techniques (helpful when gallery type images are downloaded, so user can group them with post names)

NOTE: I was not able to downloaded images from gallery post (multiple images post). Is it not implemented ?

[abhaysp95]

The branch used to make PR sensible_download_name, is based on 234bd7a2

[Turhvjbufv]

@Docile-Alligator can you please take a look at this?