enhance: add a bit-based structure to mark index-specific features

[foxspy]

issue: #795
/kind improvement

[sre-ci-robot]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.65%. Comparing base (3c46f4c) to head (e54d76a).
Report is 219 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##           main     #887       +/-   ##
=========================================
+ Coverage      0   77.65%   +77.65%     
=========================================
  Files         0       85       +85     
  Lines         0     6377     +6377     
=========================================
+ Hits          0     4952     +4952     
- Misses        0     1425     +1425     

see 85 files with indirect coverage changes

[alexanderguzhva]

/lgtm