fix: Add __typename support

[AndrewSisley]

Relevant issue(s)

Resolves #674

Description

Adds __typename support as per GQL spec.

I think I got all applicable types, but please try have a quick think if there is anything else that I may have missed (collections, groups, commits, commit-links).

I chose to add the prop on the render step, as the field is not targetable (via sort, filter etc) (we may wish to change that at somepoint, but as we dont support gql unions atm I saw no use case for that) and there seemed little point in duplicating the prop across all the documents until last minute.

Specify the platform(s) on which this was tested:

• Debian Linux

[fredcarle]

Looks good. Just a single question.

[fredcarle]

question: There are no conflicts here so why specify a name for the package? types is also shorter.

[AndrewSisley]

tradition/consistency - parserTypes is used everywhere. I have a minor preference to leaving it as is, but do let me know if you strongly prefer the removal of the alias

[fredcarle]

I always prefer to avoid aliases unless there is a conflict or if the package name is unwieldy regardless of tradition. But not a strong enough preference to push back if you want to keep it like that. That's why it was only a question.

[AndrewSisley]

Will leave as is then unless someone else chimes in before the build completes

[codecov]

Codecov Report

Merging #871 (f3d5d14) into develop (f9747f1) will increase coverage by 0.04%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop     #871      +/-   ##
===========================================
+ Coverage    59.79%   59.83%   +0.04%     
===========================================
  Files          157      157              
  Lines        17425    17443      +18     
===========================================
+ Hits         10419    10437      +18     
  Misses        6068     6068              
  Partials       938      938              

Impacted Files	Coverage Δ
core/doc.go	94.21% <100.00%> (+0.63%)	⬆️
query/graphql/mapper/mapper.go	85.22% <100.00%> (+0.09%)	⬆️