add mime-types for CBR files

[benoit-pierre]

Cf. koreader/koreader#1517 (comment).

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This change is 

[gd4c]

I think there is also:

<data android:mimeType="application/x-cbr"/>

<data android:pathPattern=".*\\.cbr"/>

somewhere in the manifest

[benoit-pierre]

application/x-cbz and the like are deprecated (cf. https://www.iana.org/assignments/media-types/application/vnd.comicbook-rar).

[Frenzie]

That doesn't necessarily matter if it's in active use. :-) (I'm not saying it is or isn't.)