Create GUI config folder before copying config

[arjo129]

🦟 Bug fix

Fixes #
I should have filed an issue for this, however this is a tiny fix so...

Basically when I was running some worlds of my own I came accross the following error

[GUI] [Wrn] [Filesystem.cc:376] Failed to create file [/home/arjo/.ignition/gazebo/6/gui.config]: No such file or directory
[GUI] [Err] [Gui.cc:269] Failed to copy installed config [/home/arjo/workspaces/ign_ws/install/share/ignition/ignition-gazebo6/gui/gui.config] to default config [/home/arjo/.ignition/gazebo/6/gui.config].
[GUI] [Dbg] [Application.cc:130] Terminating application.
[Dbg] [SignalHandler.cc:141] Received signal[2].
[Dbg] [ServerPrivate.cc:106] Server received signal[2]
[Msg] Found no publishers on /stats, adding root stats topic
[Msg] Found no publishers on /clock, adding root clock topic
[Dbg] [ign.cc:356] Shutting down ign-gazebo-server

Summary

Turns out we were not creating the directories before copying the config files.

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

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[codecov]

Codecov Report

Merging #1092 (09d5101) into ign-gazebo6 (c603710) will increase coverage by 0.01%.
The diff coverage is 46.66%.

@@               Coverage Diff               @@
##           ign-gazebo6    #1092      +/-   ##
===============================================
+ Coverage        64.07%   64.08%   +0.01%     
===============================================
  Files              255      255              
  Lines            20051    20064      +13     
===============================================
+ Hits             12847    12859      +12     
- Misses            7204     7205       +1     

Impacted Files	Coverage Δ
src/gui/Gui.cc	61.97% <46.66%> (-2.37%)	⬇️
src/gui/plugins/plot_3d/Plot3D.cc	47.82% <0.00%> (+4.34%)	⬆️

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[chapulina]

Thanks! I fixed one instance on #1070, but forgot about this one.

I rebased to ign-gazebo6 and pushed a style fix, plus an extra check.

[arjo129]

@osrf-jenkins retest this please.