[FL-977] Internal Storage (#455)

* Add littlefs submodule
* Furi: add mutex in logging, fix issues with corrupted printf
* ApiHal: disable debug traces in ble glue
* App-loader: more logs
* Passport: fix invalid DolphinState usage
* ApiHal, linker script: flash API is now aware of free space, complete abstraction layer for storage
* Internal Storage: littlefs based storage services with key value API. Migrate dolphin state to new storage API.

applications/internal-storage/internal-storage.h

@@ -0,0 +1,40 @@
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+/* Internal storage state */
+typedef enum {
+    InternalStorageStateInitializing,
+    InternalStorageStateReady,
+    InternalStorageStateBroken,
+} InternalStorageState;
+
+typedef struct InternalStorage InternalStorage;
+
+/** Read key, blocking api
+ * @param internal_storage - InternalStorage instance
+ * @param key - file name to read data from
+ * @param buffer - pointer to data buffer
+ * @param size - buffer size
+ * @return negative on error, otherwise data read
+ */
+int internal_storage_read_key(
+    InternalStorage* internal_storage,
+    const char* key,
+    uint8_t* buffer,
+    size_t size);
+
+/** Write key, blocking api
+ * @param internal_storage - InternalStorage instance
+ * @param key - file name to store data to
+ * @param buffer - pointer to data buffer
+ * @param size - buffer size
+ * @return negative on error, otherwise data written
+ */
+int internal_storage_write_key(
+    InternalStorage* internal_storage,
+    const char* key,
+    uint8_t* buffer,
+    size_t size);