Updating omnisharp.json doesn't respect %OMNISHARPHOME%

**Product and Version Used**:
v3.0.0 from Visual Studio Marketplace
**Steps to Reproduce**:
Install Roslynator and use Visual Studio Code with environment variable `%OMNISHARPHOME%` set to any location besides `~/`
**Actual Behavior**:
Extension updates `~/.omnisharp/omnisharp.json`
**Expected Behavior**:
Extension updates `%OMNISHARPHOME%/.omnisharp/omnisharp.json`

Omnisharp added this option back in https://github.com/OmniSharp/omnisharp-roslyn/pull/1317
I noticed it because I use a portable install of VSCode on a flash drive and have my data folder on the flash drive. Roslynator has been creating a `.omnisharp/omnisharp.json` file in my local computer account folder on every launch. I've already put the appropriate settings in my actual `omnisharp.json` file