Move tests to relevant subprojects (#615)

- Moved test projects to the parent project they belong to
- Improved test stability/corectness
- Improved recursive directory deletion by safely ignoring current- and parent-directory entries.
- Update docs

TactilityKernel/tests/source/dispatcher_test.cpp

@@ -0,0 +1,25 @@
+#include "doctest.h"
+#include <tactility/freertos/task.h>
+#include <tactility/concurrent/dispatcher.h>
+
+TEST_CASE("dispatcher test") {
+    DispatcherHandle_t dispatcher = dispatcher_alloc();
+    CHECK_NE(dispatcher, nullptr);
+
+    int count = 0;
+    auto error = dispatcher_dispatch(dispatcher, &count, [](void* context) {
+        int* count_ptr = static_cast<int*>(context);
+        (*count_ptr)++;
+    });
+
+    CHECK_EQ(error, ERROR_NONE);
+    vTaskDelay(1);
+
+    CHECK_EQ(count, 0);
+
+    CHECK_EQ(dispatcher_consume(dispatcher), ERROR_NONE);
+    CHECK_EQ(count, 1);
+
+    dispatcher_free(dispatcher);
+}
+