Add flag for reading ids from geojson source

[montzkie18]

GeoJSON: Expose use_id_from_source datasource parameter to load features with their original ids from the source. Should address #4227

Things to note here:

• Added a separate Spirit X3 rule for features that have an ID. This means by default parsing without any flags set will continue to ignore Feature.id. But once the flag is set, it will throw an error for invalid ids (e.g. string, null, etc...)
• Used feature.use_id_from_source() to check which grammar to use. I figured it can also be used by other plugins if they want to make it as an option.
• All instances where this flag is required is set to false by default. It should not change behavior for downstream packages.
• Since this is opt-in, I don't think it breaks the original design decision to ensure Feature.ids as unique internally.

Depends on this PR: mapnik/test-data#23

[montzkie18]

hi @artemp - any chance I can get a review for this one?

[artemp]

hi @artemp - any chance I can get a review for this one?

@montzkie18 - Yes, I'll find time asap. Thanks for your contribution!

[artemp]

@montzkie18 - Could you check test data is updated, I'm getting

could not get file mapping for ./test/data/json//feature-with-id.json

thanks.

[montzkie18]

Hi @artemp - thanks for looking into this.

Could you check test data is updated

The updated test data is pushed to this PR: mapnik/test-data#23
I'm not sure how to best handle submodules update here without that PR getting merged first.
Should I point the submodule in this PR temporarily to the forked repo and branch?

EDIT: nvm, I pushed the submodule changes here with the correct git hash

[codecov]

Codecov Report

Merging #4228 (e7bb0ac) into master (fb2e45c) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #4228   +/-   ##
=======================================
  Coverage   71.86%   71.86%           
=======================================
  Files         446      446           
  Lines       23271    23272    +1     
=======================================
+ Hits        16723    16724    +1     
  Misses       6548     6548           

Impacted Files	Coverage Δ
include/mapnik/feature.hpp	100.00% <ø> (ø)
include/mapnik/feature_factory.hpp	100.00% <100.00%> (ø)
plugins/input/geobuf/geobuf.hpp	84.51% <100.00%> (ø)
plugins/input/geojson/geojson_datasource.cpp	97.11% <100.00%> (+0.01%)	⬆️

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