Tech debt: refactor the SSMProvider class to implement the get_multiple method

[leandrodamascena]

Why is this needed?

Currently, the SSMProvider class does not implement the get_multiple method and we lose the ability to check environment variables and others.
We can't fix it now because this is a breaking change, but we need to fix it in Powertools v3.

Original discussion: https://github.com/aws-powertools/powertools-lambda-python/pull/3241/files#r1371498301

Which area does this relate to?

Parameters

Suggestion

No response

Acknowledgment

• This request meets Powertools for AWS Lambda (Python) Tenets
• Should this be considered in other Powertools for AWS Lambda languages? i.e. Java, TypeScript, and .NET

[leandrodamascena]

Closed via #4785