SerialAdapterXtermJS doesn’t detect xterm.js in ESM builds (window.Terminal is undefined)

[zero11-0203]

In pure ESM import (import { Terminal } from '@xterm/xterm'), nothing is put on window, so the adapter never instantiates the terminal.

[copy]

Possible solutions:

• document that esm users need to add window["Terminal"] = Terminal somewhere
• accept the Terminal constructor as a parameter to V86

Feel free to send a PR for either (or both)