Util function to convert from `std::ops::Range<usize>` to `tower_lsp::lsp_types::Range`

[kmaasrud]

The former is simply an index-range, while the latter is a range of two Positions, each represented by line/col numbers. This does not seem to be as trivial as I hope to convert between.

To make things harder, the ranges mdzk give for each link is obviously based on the content of the note when parsing links. This content has all the front matter stripped. Not only that, but the note.content that is stored, is the CommonMark-form, which means that all wikilinks are stored as their CommonMark equivalent. This might need to be handled inside mdzk itself.