[FL-1926] Flipper File Format addons (#753)

* Flipper file format: remove C wrapper
* Flipper file format: open append, float, uint32_t as array, delete key, value count
* Flipper file format: fix scratchpad location
* Flipper file format: add EOL on append
* SubGHZ keystore: update encryption type read and write
* Flipper File Format: enhanced version
* Flipper File Format: fix naming
* Flipper File Format: fix "open" subset naming
* Flipper File Format: tests
* Flipper File Format: file helper naming
* SubGHZ keystore: merge with current state of flipper file format
* Flipper File Format:  update make recipe
* Flipper File Format: open new file method

lib/flipper_file/flipper_file_helper.h

@@ -0,0 +1,51 @@
+#pragma once
+#include <stdint.h>
+#include <mlib/m-string.h>
+#include <storage/storage.h>
+#include "file_helper.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern const char* flipper_file_filetype_key;
+extern const char* flipper_file_version_key;
+extern const char flipper_file_delimiter;
+extern const char flipper_file_comment;
+
+/**
+ * Reads a valid key from a file as a string.
+ * After reading, the rw pointer will be on the flipper_file_delimiter symbol.
+ * Optimized not to read comments and values into RAM.
+ * @param file 
+ * @param key 
+ * @return true on success read 
+ */
+bool flipper_file_read_valid_key(File* file, string_t key);
+
+/**
+ * Sets rw pointer to the data after the key
+ * @param file 
+ * @param key 
+ * @return true if key was found 
+ */
+bool flipper_file_seek_to_key(File* file, const char* key);
+
+/**
+ * Write key and key delimiter
+ * @param file 
+ * @param key 
+ * @return bool 
+ */
+bool flipper_file_write_key(File* file, const char* key);
+
+/**
+ * Get scratchpad name and path
+ * @param name 
+ * @return bool 
+ */
+bool flipper_file_get_scratchpad_name(const char** name);
+
+#ifdef __cplusplus
+}
+#endif