refactor: add filter to searchable mixin

[xiaodemen]

#590

[codecov]

Codecov Report

Merging #598 into theme-dls will decrease coverage by <.01%.
The diff coverage is 95%.

@@              Coverage Diff              @@
##           theme-dls     #598      +/-   ##
=============================================
- Coverage      74.69%   74.68%   -0.01%     
=============================================
  Files            155      155              
  Lines           5093     5095       +2     
  Branches        1078     1078              
=============================================
+ Hits            3804     3805       +1     
- Misses           906      907       +1     
  Partials         383      383

Impacted Files	Coverage Δ
packages/veui/src/mixins/searchable.js	96.49% <95%> (-1.7%)	⬇️

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