SA1130: Handle optional named arguments correctly

[wdolek]

Fixes #3279, NullReferenceException is thrown when delegate is used as (optional) named parameter and argument index doesn't match method signature.

Fix is handling special case when argument is used with name, e.g. F(argName: delegate { ... }), otherwise everything works as before.

[codecov]

Codecov Report

Merging #3289 (7303762) into master (a559b3e) will increase coverage by 0.00%.
The diff coverage is 98.82%.

❗ Current head 7303762 differs from pull request most recent head 64a563c. Consider uploading reports for the commit 64a563c to get more accurate results

@@           Coverage Diff           @@
##           master    #3289   +/-   ##
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  Coverage   93.45%   93.45%           
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  Files        1029     1029           
  Lines      111170   111253   +83     
  Branches     3940     3944    +4     
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+ Hits       103891   103973   +82     
- Misses       6263     6264    +1     
  Partials     1016     1016           

[wdolek]

@sharwell is there anything else I can/should do with this MR?