feat: add filter

[veezhang]

What type of PR is this?

• bug
• feature
• enhancement

What problem(s) does this PR solve?

Issue(s) number:

#271

Description:

How do you solve it?

Special notes for your reviewer, ex. impact of this fix, design document, etc:

[codecov-commenter]

Codecov Report

Patch coverage: 94.16% and project coverage change: +0.10 🎉

Comparison is base (1cd45ee) 90.20% compared to head (5c49e51) 90.30%.

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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #274      +/-   ##
==========================================
+ Coverage   90.20%   90.30%   +0.10%     
==========================================
  Files          75       76       +1     
  Lines        3350     3426      +76     
==========================================
+ Hits         3022     3094      +72     
- Misses        323      326       +3     
- Partials        5        6       +1     

Impacted Files	Coverage Δ
pkg/spec/base/builder_mock.go	0.00% <0.00%> (ø)
pkg/importer/importer.go	95.38% <57.14%> (-4.62%)	⬇️
pkg/errors/import.go	100.00% <100.00%> (ø)
pkg/manager/manager.go	100.00% <100.00%> (ø)
pkg/spec/base/builder.go	100.00% <100.00%> (ø)
pkg/spec/base/filter.go	100.00% <100.00%> (ø)
pkg/spec/v3/edge.go	100.00% <100.00%> (ø)
pkg/spec/v3/graph.go	100.00% <100.00%> (ø)
pkg/spec/v3/node.go	100.00% <100.00%> (ø)

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