Disallow function expressions at the root level

ESLint's [`func-style`][1] allows us to enforce a particular type of function style, either declarations or expressions.^[\[1\]][1] Is there merit in enforcing one style over the other?

[1]:https://eslint.org/docs/rules/func-style

Start by reading the linked ESLint func-style rule documentation and inspect the repository's ESLint configuration entry points. Determine whether root-level function expressions should be disallowed and which style should be enforced. Done means the policy is decided and the configuration and related checks consistently enforce it.

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