Set Fallback Image for broken Thumbnails

[ntbm]

Added a Fallback Image for the MangaCard onError, this allows the proper css scalings to work and thus fixing the scaling issue.
Fixes: #49

Please ignore the Backbutton next to the Library Label. This is not included in this PR

Before

After

[AriaMoradi]

Not showing anything is the default behavior of Tachiyomi.
That image is really bad..

[ntbm]

I agree the Image is really bad. Though we still need a Fallback. I cloud just make an complete transparent svg/png so the scaling works properly.

[Syer10]

How about doing what JUI does and show a Kaomoji?

[Syer10]

JUI has this to get a random Kaomoji to display

private val ERROR_FACES = arrayOf(
    "(･o･;)",
    "Σ(ಠ_ಠ)",
    "ಥ_ಥ",
    "(˘･_･˘)",
    "(；￣Д￣)",
    "(･Д･。"
)

fun getRandomErrorFace(): String {
    return ERROR_FACES[Random.nextInt(ERROR_FACES.size)]
}

[AriaMoradi]

JUI has this to get a random Kaomoji to display

We already have those in EmptyView

[ntbm]

Same Solution now with transparency

[ntbm]

Added some comments for context