Parse negative values for numeric parser types

[Jaksenc]

Summary

• recognize parseInt and parseFloat as numeric parser types when deciding whether a required option may consume a following negative-looking value
• preserve the existing strict behavior for non-numeric-looking options such as -abc and for non-numeric option types like String
• carry the same numeric metadata through array parser specs so [Number] and [parseInt] handle separate negative values too

Fixes #52.

Verification

• npm test
• npx prettier --check index.js test.js
• git diff --check
• node --check index.js
• npx -p node@20 node node_modules/jest/bin/jest.js --coverage -w 2