[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_string.c

@@ -0,0 +1,67 @@
+#include <furi.h>
+
+#include "flipper_file.h"
+#include "flipper_file_i.h"
+#include "flipper_file_helper.h"
+
+static bool flipper_file_write_string_internal(
+    File* file,
+    const char* key,
+    const void* data,
+    const uint16_t data_size) {
+    bool result = false;
+    (void)data_size;
+
+    do {
+        result = flipper_file_write_key(file, key);
+        if(!result) break;
+
+        result = file_helper_write(file, string_get_cstr(data), string_size(data));
+        if(!result) break;
+
+        result = file_helper_write_eol(file);
+    } while(false);
+
+    return result;
+};
+
+bool flipper_file_read_string(FlipperFile* flipper_file, const char* key, string_t data) {
+    furi_assert(flipper_file);
+
+    bool result = false;
+    if(flipper_file_seek_to_key(flipper_file->file, key)) {
+        if(file_helper_read_line(flipper_file->file, data)) {
+            result = true;
+        }
+    }
+    return result;
+}
+
+bool flipper_file_write_string(FlipperFile* flipper_file, const char* key, string_t data) {
+    furi_assert(flipper_file);
+    return flipper_file_write_string_internal(flipper_file->file, key, data, 0);
+}
+
+bool flipper_file_write_string_cstr(FlipperFile* flipper_file, const char* key, const char* data) {
+    bool result = false;
+    string_t value;
+    string_init_set(value, data);
+    result = flipper_file_write_string(flipper_file, key, value);
+    string_clear(value);
+    return result;
+}
+
+bool flipper_file_update_string(FlipperFile* flipper_file, const char* key, string_t data) {
+    furi_assert(flipper_file);
+    return flipper_file_delete_key_and_call(
+        flipper_file, key, flipper_file_write_string_internal, key, data, 0);
+}
+
+bool flipper_file_update_string_cstr(FlipperFile* flipper_file, const char* key, const char* data) {
+    bool result = false;
+    string_t value;
+    string_init_set(value, data);
+    result = flipper_file_update_string(flipper_file, key, value);
+    string_clear(value);
+    return result;
+}