Open room member avatar in a media viewer (#1911)

* Open room member avatar in viewer.

The `MediaViewer` was extracted to its own library module.

* Update screenshots

* Restore KSP processor in `:libraries:mediaviewer:api`, this should generate Showkase components again.

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Co-authored-by: ElementBot <benoitm+elementbot@element.io>

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

@@ -60,4 +60,11 @@ object MimeTypes {
             else -> OctetStream
         }
     }
+
+    fun hasSubtype(mimeType: String): Boolean {
+        val components = mimeType.split("/")
+        if (components.size != 2) return false
+        val subType = components.last()
+        return subType.isNotBlank() && subType != "*"
+    }
 }