Improve type annotations

[tommie]

• The Processor data can be (more) well-typed.
• The AttrsNode can be inferred.
• "typeRoots" is allegedly meant for globals: typeRoots is not finding custom declaration file microsoft/TypeScript#22217 (comment)

[codecov]

Codecov Report

Merging #8 (6b3534f) into main (1624974) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main       #8      +/-   ##
==========================================
+ Coverage   99.15%   99.16%   +0.01%     
==========================================
  Files           4        4              
  Lines         354      361       +7     
  Branches       52       51       -1     
==========================================
+ Hits          351      358       +7     
  Misses          3        3              

Files	Coverage Δ
index.ts	100.00% <100.00%> (ø)
packages/attributes-transformer/index.ts	96.38% <100.00%> (+0.04%)	⬆️

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more