feat: replace stash_hive with quiver.cache

[sehnryr]

Proposed changes

Use quiver.cache instead of stash_hive and remove encryption.

Type of changes

What types of changes does your code introduce?

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• I have read the CONTRIBUTING doc
• My code follows the Dart coding convention
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works.
• I have commented my code, particularly in hard-to-understand areas
• I have added necessary documentation (if appropriate)

Further comments

I've replaced stash_hive for quiver.cache as there isn't the need for hard storing the cookies, and storing the cookies in the drive might cause more problem than solving some: IO issues, when 2 programs are looking at the same storage file...

As @LightIn-death and I said previously in #1, storing sensitive data in cookies is a really bad practice. Yet, I have accepted #65 as requests used hive to store its cookies and it would be dumb to not use its native encryption.

But there is a better alternative and it is to store the cookies in memory. If the end user wants to save the cookies for some next runs, this will be up to him to do that.

And also, if someone wants to implement requests into a flutter project, surely they will use their own storage system like flutter_secure_storage or shared_prefrences, and I don't think it would be good to have 2 different storage systems.