feat(selector): add node scheme

[tonybase]

No description provided.

[codecov-commenter]

Codecov Report

Merging #1932 (4f61233) into main (3990d91) will decrease coverage by 0.03%.
The diff coverage is 71.42%.

@@            Coverage Diff             @@
##             main    #1932      +/-   ##
==========================================
- Coverage   80.75%   80.71%   -0.04%     
==========================================
  Files          81       81              
  Lines        3606     3609       +3     
==========================================
+ Hits         2912     2913       +1     
- Misses        487      489       +2     
  Partials      207      207              

Impacted Files	Coverage Δ
selector/default_node.go	91.66% <60.00%> (-8.34%)	⬇️
transport/grpc/balancer.go	92.00% <100.00%> (ø)
transport/http/resolver.go	64.00% <100.00%> (ø)

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