[AWS] Use credentials and config from AWS SDK file

[aitorarjona]

Fix for #1107

This pull request adds functionality to retrieve AWS SDK config and credentials from the standard config file (~/.aws/config and ~/.aws/credentials) or env vars (more info).

Consequently, it deprecates using aws_access_key_id and aws_secret_access_key in aws Lithops config section.

This approach is not only more secure, as we avoid sending secrets to the runtime via payload, but also we support users with SSO-based accounts, which will need configure a profile in their ~/.aws/config file and retrieve their session credentials dynamically. E.g.:

[profile my-sso-profile]
sso_start_url = https://XXXXXXXX.awsapps.com/start
sso_region = us-east-1
sso_account_id = XXXXXXXXXXX
sso_role_name = XXXXXXXXXXXXXXXXX
region = us-east-1

Summary:

• Added new parameter in AWS config: config_profile.

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[aitorarjona]

@JosepSampe please don't merge yet

[aitorarjona]

@JosepSampe ready for review and merge

[aitorarjona]

@JosepSampe Hi Josep, all requests have been implemented. Please we should need this merged ASAP, we switched to an SSO-based account and the current implementation in main does not work well (and also to be ready for the next release #1137 ). Thanks!

[JosepSampe]

My last comments are about the 2 other AWS backend (Batch & EC2).

• Does the changes made here in the way to configure aws affect to those backends?
• Is it convenient to copy the changes made in the Lambda docs to the docs of Batch & EC2?
• In order to adapt the Batch & EC2 backends, is it as simple as copy the relevant code in the __init__ of the Lambda backend to the other 2 backends?

[aitorarjona]

Closing for now, #1164 partially solves the issue described