Trim and remove leading and trailing double quotes from `IdentityFile`

[Dentrax]

I recently noticed that ssh_config.Get() function does not remove leading and trailing double quotes from string. Eventually it leads to strange error:

open "/Users/furkan/bar/_config/user": no such file or directory

But this config does exist actually. Function should do something like strings.Trim(s, "\"") just before return.

Here is a minimal reproducible example:

Host foo
  IdentityFile "/Users/furkan/bar/_config/user"