refactor: deprecate util.find_node_modules_ancestor

[dundargoc]

Work on #2079.

[dundargoc]

@justinmk should we wait for the minimum supported version to be 0.10 before we do this because of vim.fs.root? Right now, the replacement we can use is vim.fs.find('node_modules', {path='/Users/dundargoc/test/a', upwards=true})[1]

[justinmk]

hould we wait for the minimum supported version to be 0.10 before we do this because of vim.fs.root? Right now, the replacement we can use is vim.fs.find('node_modules', {path='/Users/dundargoc/test/a', upwards=true})[1]

No, let's move forward with this. But let's also mention vim.fs.root in the "breadcrumbs" note "if you have Nvim 0.10 or newer".