apis/nfd: allow different types of features of the same name

[marquiz]

This patch changes the handling of NodeFeatureRules so that one feature name (say "cpu.cpuid") can hold different types of features (flags, attributes and/or instances). Requiring features to choose one single type has not been a limitation of the API itself (and there has been no validation on this) but an implementation decision.

The new evalutation logic of match expressions is such that "flags" and "attributes" are basically evaluated as an union - they are both maps but "flags" just don't have any value associated with the key. However, "instances" are handled separately as that is basically an array of maps and needs to be evaluated in a different way (loop over the array of instances and evaluate expressions against the attributes of each). Because of this difference care must be taken if mixing "instance" features with "flag" and/or "attribute" features.

Note that the API types or their validation is not changed - just the implementation of how the NodeFeatureRules are evaluated.

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[marquiz]

Cherry-picked #1672 here to make this buildable

[marquiz]

Rebased. Test coverage increased.

/assign @ArangoGutierrez

[marquiz]

ping @ArangoGutierrez

[ArangoGutierrez]

doc needs to be updated

[marquiz]

You refer to the return values? Fixed that part.

[ArangoGutierrez]

/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: eb12b95fa18456c3695a076c8d713879209af1c4

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ArangoGutierrez, marquiz

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[codecov]

Codecov Report

Attention: Patch coverage is 84.54545% with 17 lines in your changes are missing coverage. Please review.

Project coverage is 39.60%. Comparing base (c2e3de6) to head (bb565c0).
Report is 39 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1671      +/-   ##
==========================================
- Coverage   39.84%   39.60%   -0.25%     
==========================================
  Files          80       80              
  Lines        6841     7141     +300     
==========================================
+ Hits         2726     2828     +102     
- Misses       3861     4054     +193     
- Partials      254      259       +5     

Files	Coverage Δ
pkg/apis/nfd/nodefeaturerule/rule.go	74.59% <100.00%> (-7.43%)	⬇️
source/source.go	38.33% <ø> (+1.82%)	⬆️
pkg/apis/nfd/nodefeaturerule/expression.go	81.70% <83.16%> (+<0.01%)	⬆️

... and 9 files with indirect coverage changes