Simplify boolean conversion

[jkoenig134]

Readiness checklist

• I added/updated tests.
• I ensured that the PR title is good enough for the changelog.
• I labeled the PR.
• I self-reviewed the PR.

Description

Introduces the things @sebbi08 did in nmshd/typescript-rest#2, and hands over the job to do the conversion to typescript-rest.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Files with missing lines	Coverage Δ
...es/coreHttpApi/controllers/AttributesController.ts	95.74% <100.00%> (-0.50%)	⬇️

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