Use MimeTypes object instead of hard-coded strings.

libraries/androidutils/src/main/kotlin/io/element/android/libraries/androidutils/system/SystemUtils.kt

@@ -29,6 +29,7 @@ import androidx.annotation.ChecksSdkIntAtLeast
 import androidx.annotation.RequiresApi
 import io.element.android.libraries.androidutils.R
 import io.element.android.libraries.androidutils.compat.getApplicationInfoCompat
+import io.element.android.libraries.core.mimetype.MimeTypes
 
 @ChecksSdkIntAtLeast(api = Build.VERSION_CODES.O)
 fun supportNotificationChannels() = Build.VERSION.SDK_INT >= Build.VERSION_CODES.O
@@ -125,7 +126,7 @@ fun Context.startSharePlainTextIntent(
     noActivityFoundMessage: String = getString(R.string.error_no_compatible_app_found),
 ) {
     val share = Intent(Intent.ACTION_SEND)
-    share.type = "text/plain"
+    share.type = MimeTypes.PlainText
     share.addFlags(Intent.FLAG_ACTIVITY_NEW_DOCUMENT)
     // Add data to the intent, the receiving app will decide what to do with it.
     share.putExtra(Intent.EXTRA_SUBJECT, subject)