Include server in releases + other build system cleanups (#1610)

Include server in releases + other build system cleanups (#1610)

Set `LLAMA_BUILD_SERVER` in workflow so the `server` example gets build. This currently only applies to Windows builds because it seems like only Windows binary artifacts are included in releases.

Add `server` example target to `Makefile` (still uses `LLAMA_BUILD_SERVER` define and does not build by default)

Fix issue where `vdot` binary wasn't removed when running `make clean`.

Fix compile warnings in `server` example.

Add `.hpp` files to trigger workflow (the server example has one).