Add Pawchive

[towermom9]

Closes #16701

Checklist:

• Updated versionCode value in build.gradle.kts
• Updated baseVersionCode in build.gradle.kts (if updated multisrc theme code)
• Referenced all related issues in the PR body (e.g. "Closes #xyz")
• Set the contentWarning configuration in build.gradle.kts appropriately
• Have not changed source names
• Have explicitly kept the id if a source's name or language were changed
• Have tested the modifications by compiling and running the extension through Android Studio
• Have removed web_hi_res_512.png when adding a new extension
• This PR is AI-assisted, I have reviewed the changes manually and confirmed they are not slop

[towermom9]

mostly copied kemono. (removed KemonoPostDtoWrapped)
made an option called FALLBACK_LOW_RES_IMG and set it as default on, because pawchive archived all/most of kemono's broken stuff. and all of the broken stuff only shows when use_low_res_img is on.

[AwkwardPeak7]

can the code be simplified for this source? kemono code is rather old and complicated, since this is a new source, perhaps it can be stripped.

[towermom9]

Simplified the code as much as i can 😅

1. removed avatarUrl variable and formatAvatarUrl() function as pawchive doesn't add "//img." for their avatar/icons

2. removed all code related to Discord, since Pawchive doesn't have it as a service.

3. Combined duplicate code that handle low-resolution backup images into a function called toThumbnailUrl().

4. Merged PawchiveAttachmentDto and PawchiveFileDto as they do the exact same thing.

5. Added a new switch in the settings. Users can now choose whether they want to sort their list by the date a post was Added, Published, or Edited. It defaults to date published.

[MediocreLegion]

This could have used the kemono multi-src, btw. I got it working by separating the image, avatar and thumbnail CDN urls, and by copy-pasting pageListParse, just replacing KemonoPostDtoWrapped with KemonoPostDto

[AwkwardPeak7]

also please remove some of your obvious comments.