Support tmux -f option

[jfindlay]

Fixes #654. libtmux.server.Server already supports a config option, so extend the option to the tmuxp load command line.

[jfindlay]

Not sure if this change warrants a separate unit test, but I can add one if needed.

[codecov]

Codecov Report

Merging #665 (a91404d) into master (7bb97ec) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #665      +/-   ##
==========================================
+ Coverage   75.93%   75.95%   +0.02%     
==========================================
  Files           8        8              
  Lines        1180     1181       +1     
  Branches      295      295              
==========================================
+ Hits          896      897       +1     
  Misses        204      204              
  Partials       80       80              

Impacted Files	Coverage Δ
tmuxp/cli.py	73.78% <100.00%> (+0.05%)	⬆️

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[tony]

This works, the behavior is exactly like tmux proper. The configs bind to the server

If users want to launch a different tmux server with a totally separate and independent configuration, pass e socket-name (-L) or socket-path (-S)

e.g. tmuxp load yourconfig -f /dev/null -L test will launch a blank tmux server at that socket name

[tony]

@jfindlay Thank you! I will follow up with the versions this rolls out for

[tony]

@jfindlay followed up here: #654 (reply in thread)