Use in-memory thumbnail APIs when possible (#3817)

* Use in-memory thumbnail APIs when possible

* Make an exception for animated image types.

Also add `TimelineItemImageContent.thumbnailMediaRequestData` lazy property.

* Try simplifying the logic a bit more.

libraries/core/src/main/kotlin/io/element/android/libraries/core/mimetype/MimeTypes.kt

@@ -38,6 +38,7 @@ object MimeTypes {
     fun String?.normalizeMimeType() = if (this == BadJpg) Jpeg else this
 
     fun String?.isMimeTypeImage() = this?.startsWith("image/").orFalse()
+    fun String?.isMimeTypeAnimatedImage() = this == Gif || this == WebP
     fun String?.isMimeTypeVideo() = this?.startsWith("video/").orFalse()
     fun String?.isMimeTypeAudio() = this?.startsWith("audio/").orFalse()
     fun String?.isMimeTypeApplication() = this?.startsWith("application/").orFalse()