Add manual migration

[WGmg23]

Describe your suggested feature

Add an option to just use normal migration like in mihon, since it's very difficult to use it to migrate since it only shows one manga

Other details

Please

Acknowledgements

• [X] I have searched the existing issues and this is a new ticket, NOT a duplicate or related to another open issue.
• [X] I have written a short but informative title.
• [X] If this is an request for a feature in the original Tachiyomi, I am opening because multiple versions of Yōkai have been released without this feature.
• [X] If this is an issue with an extension, or a request for an extension, I should be contacting the extensions repository's maintainer/support for help.
• [X] I have updated the app to version 1.8.5.6.
• [X] I have checked through the app settings for my feature.
• [X] I will fill out all of the requested information in this form.

[null2264]

Wdym? It's already there even before I forked J2K. Browse -> Migration -> Select the source (Not the all button, the source name/icon). Alternatively you can just go to the individual entry's page, tap the triple dots -> Migrate Manga/Manhwa/Manhua.