fix(serverless-offline-sqs): resolve intrinsic & pseudo-parameter ARNs to a queueName (#200, #74)

[silouone]

Summary

extractQueueNameFromARN did a naive arn.split(':')[5], which silently produced arn:...:undefined for two common ARN shapes. ElasticMQ then rejects the poll with Missing required key 'QueueName' / MissingQueryParamRejection(QueueName), and the Lambda never fires.

• [serverless-offline-sqs] Missing QueueName #200 (@jlgouwyapizr) — an arn given as a Fn::Join object (with a nested {Ref: AWS::AccountId}) is an object, so the old switch('string') never reached extraction at all → queueName: undefined.
• [serverless-offline-sqs] Doesn't work with serverless-pseudo-parameters #74 (@maximusinc) — serverless-pseudo-parameters leaves #{AWS::AccountId} inside the ARN string; the extra :: it injects pushed split(':')[5] onto an empty segment → empty queue name.

Fix

A pure, exported resolveCfnValue flattens the intrinsic / pseudo-parameter forms an event arn can take — Ref, Fn::Join, Fn::Sub, and the #{AWS::X} / ${AWS::X} pseudo-parameters — into a plain string. The queue name is then taken as the final :-delimited segment of the resolved ARN, which is robust to any number of : the pseudo-parameters inject. The fragile switch('string') is replaced by an explicit branch that prefers an explicit queueName (the #211 override path) and otherwise derives it from the resolved ARN. A .fifo suffix is intentionally preserved.

Fn::GetAtt is already resolved to a string ARN upstream in index._resolveFn, so it deliberately has no branch here. Anything unresolvable offline (Fn::ImportValue, a Ref to a stack resource) returns undefined rather than throwing — the ARN stays visibly bad instead of silently wrong.

Behavior note: when an event sets both arn and queueName with different values, the explicit queueName now wins (the old code preferred arn). The README's documented example uses matching values, so no documented config changes.

Fixes #200
Fixes #74

Testing

• 10 new AVA cases including the exact [serverless-offline-sqs] Missing QueueName #200 (Fn::Join + Ref) and [serverless-offline-sqs] Doesn't work with serverless-pseudo-parameters #74 (#{AWS::AccountId}) repros, plus the pure-helper level (resolveCfnValue, extractQueueNameFromARN). Confirmed failing on master, passing here.
• npx ava packages/serverless-offline-sqs/test/index.js → 30/30; npx eslint packages/serverless-offline-sqs/ clean.
• No dependency/package.json changes (no lockfile regen needed).

Note: #189 (a FIFO .fifo queue-name vs ElasticMQ static-config mismatch) is a different root cause and is intentionally not claimed here — it belongs with the FIFO autocreate work.

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