Encode teal key-value as map in json

[tolikzinovyev]

Summary

Closes #753.

Test Plan

Modified unit tests.

[winder]

LGTM

[codecov-commenter]

Codecov Report

Merging #755 (4f9e86b) into develop (0cf6a71) will decrease coverage by 0.03%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop     #755      +/-   ##
===========================================
- Coverage    54.88%   54.85%   -0.04%     
===========================================
  Files           27       27              
  Lines         3817     3814       -3     
===========================================
- Hits          2095     2092       -3     
  Misses        1450     1450              
  Partials       272      272              

Impacted Files	Coverage Δ
idb/postgres/internal/encoding/types.go	66.66% <ø> (ø)
idb/postgres/internal/encoding/decode.go	64.00% <100.00%> (ø)
idb/postgres/internal/encoding/encode.go	88.28% <100.00%> (-0.27%)	⬇️

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