Standalone formatter release?

[acdha]

It would be really helpful for some of my projects if the new formatter was available in a CLI form which could be used in a pre-commit hook to have CI ensure that formatting drift doesn't creep in via editing processes not involving VS Code.

[fbricon]

It's probably doable, feel free to open a PR on the https://github.com/eclipse/lemminx repo to add a Main class for managing CLI. Our team doesn't have the bandwidth to handle such things at the moment.