Support Lambda-Extension-Accept-Feature for extension registration #882
Description
When calling the register API during extension initialization, there is an optional request header called Lambda-Extension-Accept-Feature that allows you to get the account ID associated with the Lambda function on the response body from the register API call documentation reference. The lambda-extension crate, however, has no way for consumers to add this header to the request, or to receive the accountId on the response body.
There should either be a way to opt-in to these "additional features" when registering extensions, or possibly even include the accountId by default.
Has this been considered before? Is there a preference by the maintainers for including something like that by default vs making it a parameter?