[FL-2312] Flipper format: insert OR update (#1009)

* Flipper format: seek_to_end, key_exist
* Flipper Format: insert_or_update

lib/flipper_format/flipper_format_stream_i.h

@@ -18,6 +18,17 @@ extern "C" {
  */
 bool flipper_format_stream_write_eol(Stream* stream);
 
+/**
+ * Seek to the key from the current position of the stream.
+ * Position will be at the beginning of the value corresponding to the key, if the key is found,, or at the end of the stream.
+ * @param stream 
+ * @param key 
+ * @param strict_mode 
+ * @return true key is found
+ * @return false key is not found
+ */
+bool flipper_format_stream_seek_to_key(Stream* stream, const char* key, bool strict_mode);
+
 #ifdef __cplusplus
 }
 #endif