Remove unnecessary explicit AsciiString or UnicodeString instantiation

Remove unnecessary explicit `AsciiString` or `UnicodeString` instantiation across code base.

Example:

```cpp
TheFileSystem->getFileListInDirectory(AsciiString(".\\data\\Editor\\Molds\\"), AsciiString("*.w3d"), filenameList, FALSE);
```

Simpler:

```cpp
TheFileSystem->getFileListInDirectory(".\\data\\Editor\\Molds\\", "*.w3d", filenameList, FALSE);
```