Add a GDS test case with app name which has locale null

[mregen]

fixes #863
issue was no repro but test case was added

[codecov]

Codecov Report

Merging #1501 (29f2817) into master (76afe82) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1501   +/-   ##
=======================================
  Coverage   51.93%   51.93%           
=======================================
  Files         307      307           
  Lines       58332    58332           
=======================================
+ Hits        30292    30295    +3     
+ Misses      28040    28037    -3     

Impacted Files	Coverage Δ
...c.Ua.Gds.Server.Common/ApplicationsDatabaseBase.cs	40.78% <0.00%> (-0.88%)	⬇️
...braries/Opc.Ua.Server/Subscription/Subscription.cs	54.48% <0.00%> (+0.11%)	⬆️
...raries/Opc.Ua.Server/Subscription/MonitoredItem.cs	44.09% <0.00%> (+0.60%)	⬆️

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[mrsuciu]

Looks Ok if the intention is to test the null case sporadically when the _randomSource.NextInt32(10) returns 0.