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

Tactility/Tests/Source/FileTest.cpp

@@ -0,0 +1,14 @@
+#include "doctest.h"
+#include <Tactility/file/File.h>
+
+using namespace tt;
+
+TEST_CASE("findOrCreateDirectory can create a directory tree without prefix") {
+    CHECK_EQ(file::findOrCreateDirectory("test1/test1", 0777), true);
+    CHECK_EQ(file::deleteRecursively("test1"), true);
+}
+
+TEST_CASE("findOrCreateDirectory can create a directory tree with prefix") {
+    CHECK_EQ(file::findOrCreateDirectory("/tmp/test2", 0777), true);
+    CHECK_EQ(file::deleteRecursively("/tmp/test2"), true);
+}