Add parser module

[scottgerring]

To fill the gap with Powertools for Python, we should add a parser module. This will allow us to define models as POJOs then parse, validate, and extract only what we want. The python library is built on top of Pydantic and we will need to identify a Java equivalent.

Python version: https://awslabs.github.io/aws-lambda-powertools-python/2.9.1/utilities/parser/#install

[jeromevdl]

Note that we have the lambda-event library (looks close to that) and also some utilities in the serialization module. (comparing this and this)

Can we explicitly describe what is available and what is missing (of if something can be improved)?

[scottgerring]

I will go through and diff this against python to see if we are missing anything.

[AlexeySoshin]

@scottgerring I'm curious, what's the gap with the Jackson we already have in the project?

[scottgerring]

@AlexeySoshin it's not clear that we have one - this task is more likely to be a "go and compare what we have against the python impl, and assert that we aren't missing any functionality" one