NF: BackendUtils gets better type

I had a bug due to an erroneous type sent to `toJsonBytes`. I believe
it's better to indicates explicitly which type we know it can accept,
and if needed add more type.

Author: Arthur-Milchior

AnkiDroid/src/main/java/com/ichi2/libanki/TemplateManager.kt

@@ -218,7 +218,7 @@ class TemplateManager {
                         backend.renderUncommittedCardLegacy(
                             _note.toBackendNote(),
                             _card.ord,
-                            BackendUtils.toJsonBytes(_template!!.deepClone()),
+                            BackendUtils.toJsonBytes(_template!!),
                             fillEmpty,
                             true,
                         )

AnkiDroid/src/main/java/com/ichi2/libanki/backend/BackendUtils.kt

@@ -20,6 +20,7 @@ package com.ichi2.libanki.backend
 
 import com.google.protobuf.ByteString
 import com.ichi2.libanki.utils.LibAnkiAlias
+import com.ichi2.utils.JSONObjectHolder
 import net.ankiweb.rsdroid.RustCleanup
 import org.json.JSONArray
 import org.json.JSONObject
@@ -31,12 +32,14 @@ object BackendUtils {
     fun jsonToArray(json: ByteString): JSONArray = JSONArray(json.toStringUtf8())
 
     @RustCleanup("Confirm edge cases")
-    fun toByteString(conf: Any?): ByteString {
+    fun toByteString(conf: JSONObject): ByteString {
         val asString: String = conf.toString()
         return ByteString.copyFromUtf8(asString)
     }
 
     @RustCleanup("Confirm edge cases")
     @LibAnkiAlias("to_json_bytes")
-    fun toJsonBytes(json: Any?): ByteString = toByteString(json)
+    fun toJsonBytes(json: JSONObject): ByteString = toByteString(json)
+
+    fun toJsonBytes(json: JSONObjectHolder): ByteString = toJsonBytes(json.jsonObject)
 }