feat(proto): implement Interval and Nothing

[ernado]

Ref: #120

[codecov-commenter]

Codecov Report

Merging #135 (92595c4) into main (a62ef09) will decrease coverage by 0.22%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##             main     #135      +/-   ##
==========================================
- Coverage   76.02%   75.80%   -0.23%     
==========================================
  Files         120      122       +2     
  Lines        5710     5782      +72     
==========================================
+ Hits         4341     4383      +42     
- Misses       1164     1189      +25     
- Partials      205      210       +5     

Impacted Files	Coverage Δ
cht/config.go	57.14% <ø> (ø)
proto/column.go	78.94% <ø> (ø)
proto/col_interval.go	53.12% <53.12%> (ø)
proto/col_nothing.go	76.92% <76.92%> (ø)
proto/col_auto.go	73.49% <78.57%> (+1.03%)	⬆️
client.go	72.82% <0.00%> (-1.05%)	⬇️
query.go	66.10% <0.00%> (-0.64%)	⬇️

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