Add unit tests for http and grpc

[dfarr]

TODO:

• add all grpc tests

Closes #64
Closes #65

[codecov]

Codecov Report

Merging #75 (c038100) into main (74a435d) will decrease coverage by 5.62%.
Report is 1 commits behind head on main.
The diff coverage is 66.40%.

@@            Coverage Diff             @@
##             main      #75      +/-   ##
==========================================
- Coverage   70.80%   65.19%   -5.62%     
==========================================
  Files          41       49       +8     
  Lines        4114     5714    +1600     
==========================================
+ Hits         2913     3725     +812     
- Misses        990     1729     +739     
- Partials      211      260      +49     

Files	Coverage Δ
internal/app/coroutines/timeoutPromise.go	84.90% <ø> (-0.28%)	⬇️
...rnal/app/subsystems/aio/store/postgres/postgres.go	68.63% <100.00%> (ø)
internal/app/subsystems/aio/store/sqlite/sqlite.go	70.74% <100.00%> (ø)
internal/app/subsystems/aio/store/test/cases.go	71.42% <ø> (ø)
internal/app/subsystems/aio/store/test/utils.go	100.00% <100.00%> (ø)
internal/app/subsystems/api/test/utils.go	100.00% <100.00%> (ø)
internal/kernel/types/api_request.go	97.29% <100.00%> (ø)
internal/kernel/types/api_response.go	96.55% <ø> (+18.77%)	⬆️
pkg/promise/promise.go	74.13% <100.00%> (+11.63%)	⬆️
pkg/promise/record.go	67.85% <100.00%> (ø)
... and 11 more

... and 3 files with indirect coverage changes

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