refactor: pkg/id, use ID aliases, move JSON schemas

[rot1024]

• Fix behavior of methods of Ids when they are zero values
• Fix unit tests, Increase coverage of unit tests for pkg/id
• Rename *IDToKeys funcs to *IDsToStrings in pkg/id
• Define and use ID aliases for each domains (pkg/*/id.go) to shorten codes and clarify dependencies between packages
• Move JSON schemas from the project root to schemas directory
• Remove unnecessary comments

[codecov]

Codecov Report

Merging #97 (436a119) into main (8b0c250) will increase coverage by 0.03%.
The diff coverage is 55.43%.

@@            Coverage Diff             @@
##             main      #97      +/-   ##
==========================================
+ Coverage   32.58%   32.61%   +0.03%     
==========================================
  Files         294      299       +5     
  Lines       18906    18928      +22     
==========================================
+ Hits         6160     6174      +14     
- Misses      11938    11943       +5     
- Partials      808      811       +3     

Impacted Files	Coverage Δ
internal/infrastructure/memory/container.go	0.00% <ø> (ø)
internal/infrastructure/memory/scene_lock.go	0.00% <0.00%> (ø)
internal/infrastructure/mongo/mongodoc/layer.go	0.00% <0.00%> (ø)
...ernal/infrastructure/mongo/mongodoc/scene_align.go	0.00% <0.00%> (ø)
pkg/builtin/main.go	71.42% <ø> (ø)
pkg/dataset/dataset.go	35.84% <ø> (ø)
pkg/dataset/field.go	33.33% <ø> (ø)
pkg/dataset/graph_loader.go	0.00% <0.00%> (ø)
pkg/dataset/loader.go	0.00% <0.00%> (ø)
pkg/dataset/schema.go	18.18% <ø> (ø)
... and 200 more