Support tabs in `nomad fmt`

### Proposal

nomad fmt should support using tabs for indentation. Using two spaces is less accessible. Meanwhile, by using tabs, each team member can choose the visual level of indentation based on the file complexity and their visual needs.

This can be enabled via a cli flag `nomad fmt -tabs` or by respecting the `.editorconfig`

Start by locating the `nomad fmt` entry point and the formatter configuration and test coverage. Compare the proposed CLI flag and `.editorconfig` approaches, then define the selected behavior and add tests showing that tab indentation is honored when formatting is complete.

Written by the indexing model from the issue text.