Temporarily backport app updates from apps repo

applications/external/mayhem_morseflash/uart_validators.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <core/common_defines.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+typedef struct ValidatorIsFile ValidatorIsFile;
+
+ValidatorIsFile* validator_is_file_alloc_init(
+    const char* app_path_folder,
+    const char* app_extension,
+    const char* current_name);
+
+void validator_is_file_free(ValidatorIsFile* instance);
+
+bool validator_is_file_callback(const char* text, FuriString* error, void* context);
+
+#ifdef __cplusplus
+}
+#endif