Make it work on windows

Make it work on windows

Apparently passing :coding 'no-conversion to make-process on windows
is essential to receive any text at all in the process filter.

Also needed to tweak uri-to-path and path-to-uri.

Thanks to lsp-mode.el for these hints

* eglot.el (eglot--make-process): Pass :coding 'no-conversion to
make-process.
(eglot--path-to-uri): Add a forward slash if windows-nt.
(eglot--uri-to-path): Remove a forward slash if windows-nt.
(eglot--server-textDocument/publishDiagnostics): Simplify and use
eglot--uri-to-path.