bug(windows): sfx archives generated for Keyman are probably technically invalid

Per comments from https://quality.embarcadero.com/browse/RSP-17889 (copied here for ref):

* ZIP archive contains offsets relative to beginning of stream/file. So:

```
CreateZip('example.zip', ParamStr(0)) - example.zip is created with offsets relative to beginning of example.zip, OK
UnzipZip('example.zip') - OK
CreateSfx(ParamStr(0), 'example.zip', 'example-zip.exe', offset) - example-zip.exe is created with appended example.zip, but the offsets are not updated, NOT CORRECT
UnzipZipAtOffset('example-zip.exe', offset) - example.zip is extracted and copied to TMemoryStream, then extracted, OK
UnzipSfx('example-zip.exe', offset) - trying to extract from some offset fails, because ZIP archive offsets are relative to beginning of stream, not to current stream position, FAIL
```

The main difference is how to create "sfx":

* 1st copy EXE to output stream
* then create ZIP archive using the same output stream

Note, using `TProxySubrangeStream` it is possible to embed / extract ZIP archive at some not-zero stream position without copying ZIP archive into another stream / file, eg:

```
TProxySubrangeStream.Create(InputStream, InputStream.Position, -1, False)
```

Given things are 'working' for now we will leave this at present. But something to check in on in the future.