Add select filter

[ogonkov]

Summary

Proposed change:

• Add select filter

Closes #282 .

Checklist

I've completed the checklist below to ensure I didn't forget anything. This makes reviewing this PR as easy as possible for the maintainers. And it gets this change released as soon as possible.

• Proposed change helps towards purpose of this project.
• Documentation is added / updated to describe proposed change.
• Tests are added / updated to cover proposed change.
• Changelog has an entry for proposed change (if user-facing fix or feature).

[codecov-io]

Codecov Report

Merging #1278 into master will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1278      +/-   ##
==========================================
+ Coverage   89.53%   89.55%   +0.01%     
==========================================
  Files          22       22              
  Lines        3020     3025       +5     
==========================================
+ Hits         2704     2709       +5     
  Misses        316      316              

Impacted Files	Coverage Δ
nunjucks/src/filters.js	96.18% <100.00%> (+0.06%)	⬆️

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[ogonkov]

@fdintino can you look at this one pls?

[fdintino]

I've merged this into master, but github appears to be having some sort of service outage so it's not yet being reflected in the UI. I'll hold off temporarily on merging your reject filter PR.

[fdintino]

I've merged this into master, but github appears to be having some sort of service outage so it's not yet being reflected in the UI. I'll hold off temporarily on merging your reject filter PR.

[ogonkov]

reject filter is not ready yet to be merged

[fdintino]

Ah, right. Thanks for this PR! Merged in 2031bf2