"Multi" as language instead of "All"

[AntsyLich]

Describe why this should be added

"Multi" will be more appropriate to classify source/extension as they contain multiple languages and not all.

Other details

No response

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 issue with the app itself, I should be opening an issue in the app repository.
• [X] I have updated the app to version 0.13.5.
• [X] I have updated all installed extensions.
• [X] I will fill out all of the requested information in this form.

[stevenyomi]

Related: https://github.com/tachiyomiorg/tachiyomi/pull/7200#issuecomment-1139148769

[arkon]

App rewording was merged for next release. You'd want to also update the website.