Kubernetes Executor: Allow executor pod customisation, at least allow annotations.
Description
We want to use kube2iam to give permissions to access particular AWS resources to executors but there is no way to configure annotations on the gitlab executor pod created by the runner, only volumes / limits can be configured.
Proposal
At the moment the number of properties configurable in the executor, created by the runner is limited to volumes and resource limits (plus a few other things). The list of things possible to configure has been slowly growing but still limited. Best case would be to create an escape hatch to allow customising any part of the pod resource to support any future kube changes without requiring runner changes, but in the interim an ability to add annotations to the executor pod would solve my current problem.