Support format modificationsIfAvailable

[rmallampalli]

VS Code currently has a setting editor.formatOnSaveMode which allows to format only the modified lines according to source control. Currently if it is set to modifications or modificationsIfAvailable, ruff fails silently. Only setting it to file works: please consider throwing an error if the setting is changed. I would also like the modificationsIfAvailable option to be supported.

My use case is as follows: in certain codebases full files cannot be formatted as that would make reading the diffs between working state and old commits quite difficult.

This may be related to this open issue in the ruff repo.

I use the binary shipped with v2023.44.0 of the extension.
My settings file:

    "[python]": {
        "editor.defaultFormatter": "charliermarsh.ruff",
    },
    "notebook.formatOnSave.enabled": true,
    "editor.formatOnSaveMode": "modifications",
    "inlineChat.showDiff": false,
    "editor.formatOnPaste": true,
    "editor.formatOnType": true,
    "editor.formatOnSave": true

[MichaReiser]

Here a link to the announcement of the new setting. It requires support for the Range formatting LSP operation