Response files not working correctly

Look at below output from console. I think rsp file is treated just as 1 argument not as command, options and arguments. Output is from latest beta version.

```
D:\devdiv\vscodecoverage\artifacts>more cov.rsp
merge -r *.coverage

D:\devdiv\vscodecoverage\artifacts>dotnet .\bin\Microsoft.CodeCoverage.Console\Release\netcoreapp3.1\Microsoft.CodeCoverage.Console.dll [parse] merge -r *.coverage
[ codecoverage [ merge [ -r ] <*.coverage> *[ --output ] *[ --output-format ] ] ]

D:\devdiv\vscodecoverage\artifacts>dotnet .\bin\Microsoft.CodeCoverage.Console\Release\netcoreapp3.1\Microsoft.CodeCoverage.Console.dll [parse] @cov.rsp
![ codecoverage ] ???--> merge -r *.coverage
```