feat: set name of middleware function to improve interop with monitoring tools

[satazor]

Set name of middleware function to improve interop with monitoring tools.

Tools like @opentelemetry/instrumentation-koa use function names to generate span names. These names appear in UI of monitoring tools, such as datadog.

Because the returned function doesn't have a name, there's no hint about the actual middleware associated with that span. See below:

In v4 the returned middleware had a name but in v5 got removed, see:

bodyparser/index.js

Line 63 in 5678a79

return async function bodyParser(ctx, next) {

.

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• I have rebased all commits where necessary so that reviewing this pull request can be done without having to merge it first.
• I have written a commit message that passes commitlint linting.
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[fengmk2]

+1

[fengmk2]

• @koa/[email protected]

[satazor]

@fengmk2 thanks for the quick merge and release 🙏