feat(knext): add knext vector store interface

[xionghuaidong]

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Please upload report for BASE (master@c9a775d). Learn more about missing BASE report.

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #107   +/-   ##
=========================================
  Coverage          ?   50.78%           
  Complexity        ?      256           
=========================================
  Files             ?      651           
  Lines             ?    21719           
  Branches          ?     3540           
=========================================
  Hits              ?    11029           
  Misses            ?     9387           
  Partials          ?     1303           

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.