Using AWS secrets in includeConfig doesn't work

[bentsherman]

We added the ability to use secrets in the includeConfig path in #4840 . This works for local secrets, but not AWS secrets, because AWS secrets requires the xpack-amzn plugin and the config is resolved before plugins are loaded, since the config may include additional plugins.

To fix this I think we would need to load plugins in two phases, adding an "early" phase which happens before the config is resolved.

Not sure how much demand there is for this use case, but it would include any AWS Batch run in Seqera Platform that loads a private config using a secret credential.

cc @markpanganiban

[pditommaso]

Bit ugly, because plugins depends on the config 🤦

[pditommaso]

Likely assuming the AWS config does not rely in the config setting it's possible to load the AWS plugin to resolve the secrets

[pditommaso]

There are two possible approaches:

1. Fetching the branch to be used via the provider API, likely here
2. or using git remote via jgit (see here)

Tagging @tom-seqera for visibility