Add support for Hashicorp Vault's AWS Secrets Engine

Problem to solve

Customers that have secrets stored in Vault's AWS secrets engine and will want to use them in GitLab CI.

Intended users

Sasha (Software Developer)

User experience goal

As a user, I want to be able to select AWS as a secrets engine parameter in my yaml for Vault.

Proposal

Update CI syntax and Runner so that jobs can use secrets stored in Vault's AWS secret engine - https://www.vaultproject.io/api/secret/aws

Support the ability for these secrets to be referenceable directly from the pipeline, reducing the need for additional calls through the vault api or cli to access these secrets.

Documentation

This will need documentation

What does success look like, and how can we measure that?

We will need to instrument tracking of users with AWS secrets enabled

What is the type of buyer?

GitLab Premium