Generate SSH config

[steiler]

Generate SSH config that:

• Set the Username for the nodes
• Set StrictHostKeyChecking=no
• Set UserKnownHostsFile=/dev/null

Been thinking of using wildcard match, but in case the prefix of nodes is set to ""

name: MyTopoName 
prefix: ""

The Names would not have a prefix name of "clab-" anymore. So going with individual entries is the best option.

Implementing #1659

[hellt]

@steiler thanks for this, good quality of life improvement IMO
if you're happy with my polishing stuff I am good with merging this

[steiler]

lgtm

[codecov]

Codecov Report

Merging #1660 (8aa9e02) into main (670d658) will increase coverage by 0.18%.
Report is 1 commits behind head on main.
The diff coverage is 64.70%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1660      +/-   ##
==========================================
+ Coverage   50.96%   51.15%   +0.18%     
==========================================
  Files         136      137       +1     
  Lines       13188    13239      +51     
==========================================
+ Hits         6721     6772      +51     
+ Misses       5726     5721       -5     
- Partials      741      746       +5     

Files	Coverage Δ
types/topo_paths.go	70.43% <100.00%> (+0.52%)	⬆️
cmd/deploy.go	65.29% <40.00%> (-0.45%)	⬇️
cmd/destroy.go	70.06% <40.00%> (-0.99%)	⬇️
clab/sshconfig.go	69.23% <69.23%> (ø)

... and 3 files with indirect coverage changes