Implemented Files app (#33)

- Created Files app to browse PC and ESP32 files.
- Refactored toolbars so it's now a proper widget and allows for changing its properties from the app
- Toolbar now has extra action buttons
- Settings app now has a proper icon
- Minor cleanup in Desktop app

tactility-core/src/string_utils.c

@@ -0,0 +1,26 @@
+#include "string_utils.h"
+#include <string.h>
+
+int tt_string_find_last_index(const char* text, size_t from_index, char find) {
+    for (size_t i = from_index; i >= 0; i--) {
+        if (text[i] == find) {
+            return (int)i;
+        }
+    }
+    return -1;
+}
+
+bool tt_string_get_path_parent(const char* path, char* output) {
+    int index = tt_string_find_last_index(path, strlen(path) - 1, '/');
+    if (index == -1) {
+        return false;
+    } else if (index == 0) {
+        output[0] = '/';
+        output[1] = 0x00;
+        return true;
+    } else {
+        memcpy(output, path, index);
+        output[index] = 0x00;
+        return true;
+    }
+}

tactility-core/src/string_utils.h

@@ -0,0 +1,29 @@
+#pragma once
+
+#include <stdbool.h>
+#include <stdio.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Find the last occurrence of a character.
+ * @param[in] text the text to search in
+ * @param[in] from_index the index to search from (searching from right to left)
+ * @param[in] find the character to search for
+ * @return the index of the found character, or -1 if none found
+ */
+int tt_string_find_last_index(const char* text, size_t from_index, char find);
+
+/**
+ * Given a filesystem path as input, try and get the parent path.
+ * @param[in] path input path
+ * @param[out] output an output buffer that is allocated to at least the size of "current"
+ * @return true when successful
+ */
+bool tt_string_get_path_parent(const char* path, char* output);
+
+#ifdef __cplusplus
+}
+#endif