Update omnisharp.lua

[Ren-B-7]

Add fdfind inline if statement, to fix the plugin for Ubuntu users

Added and tested inline statement for checking fd/ fdfind and locating root for directory

[Ren-B-7]

Cant use vim.fn.executable() as a standalone, it returns an int {0, 1}, thus the inline if statement would always see it as true, and always use fdfind, even if not installed, or installed as fd
Needs to be explicit 1 to use fdfind

[jmartins-sh]

This test asserts the fd. Do we need to make any changes to it?

[Ren-B-7]

The issue here is that the fd package is named fdfind on ubuntu and debian, since a package with the nickname fd already exists.

This update is to basically detect does fdfind exist? If yes then call that, with the fallback of fd.

Wish there was another way but i cant get the fd command passed down to child terminals with zsh. Thus this is a solution, might have to update the assert line as well, but it works for me on Ubuntu currently. (Working from my personal fork)