eslintrc rules may be invalid

Discovered as part of unrelated changes: the rule to ignore missing imports is `n/no-missing-imports`, not `node/no-missing-imports`.

The .estlintrc.json inherits from gts, and uses module source, so the rule may never be used anyway, but it would be useful to confirm the configuration is correct and update it if required.

Inspect .estlintrc.json and compare the missing-import rule with the inherited gts configuration and module source setting. Confirm whether the rule is active, correct the configuration if needed, and verify that the resulting ESLint configuration is valid.

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