improved parsing ssh-config

[Viknet]

1. Interpolation of Tokens for properties "HostName", "IdentityAgent", "IdentityFile", "ProxyCommand":

Host viknet
  Hostname %h-dev.microsoft.com
  IdentityAgent /var/tmp/ssh/%u-agent-socket
  IdentityFile %d/.ssh/id_rsa.pub
  ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p

2. Better parsing Host section line, when it has several values:

Host github.com gitlab.com *.microsoft.com

3. Type safety for computed HostConfiguration

[AGI-chandler]

I found the extension was unable to parse my ~/.ssh/config in the same way ssh command can.
ℰ.ℊ. using a config such as:

# Global options
IdentitiesOnly yes
# Domain options
Host *.domain.com
  IdentityFile ~/.ssh/id1
  IdentityFile ~/.ssh/id2
  IdentityFile ~/.ssh/id3
# Host options
Host host1
  Hostname host1.domain.com
  User user1
  Port port1

In the terminal ssh host1 connects to the defied user1@host1.domain.com:port1 using the first of the specified IdentityFile's that works and disconnects if none work, never prompting for a password. Whereas, in Codium with this extension, if I tell it to connect to "host1" it will connect to user1@host1.domain.com:port1 but it does not try any of my IdentityFile's and falls back to password auth.  The conclusion is the extension only uses the most specific options for a host (or the last matching block?).

I found that if I made a new config block with all the required options, ℯ.ℊ.:

Host vsc-host1
  IdentitiesOnly yes
  IdentityFile ~/.ssh/id1
  IdentityFile ~/.ssh/id2
  IdentityFile ~/.ssh/id3
  Hostname host1.domain.com
  User user1
  Port port1

then tell the extension to connect to "vsc-host1" it will work properly without asking for a password.

Does your pull request address this, so connecting to "host1" works as expected, and no need for separate "vsc-host1" config block?  Or, I have a different issue I should report separately?

Thanks!