feat: Add alb lambda event support to Parser utility

[ran-isenberg]

feat: Add alb lambda event support to Parser utility #228

[heitorlessa]

Looks great!! Two questions:

1. Could you update the docs too?
2. Do we need an envelope for the body field?

Here's the line where we tell customers what models Parser offers: https://github.com/awslabs/aws-lambda-powertools-python/blob/develop/docs/content/utilities/parser.mdx#extending-built-in-models

[ran-isenberg]

Looks great!! Two questions:

1. Could you update the docs too?
2. Do we need an envelope for the body field?

Here's the line where we tell customers what models Parser offers: https://github.com/awslabs/aws-lambda-powertools-python/blob/develop/docs/content/utilities/parser.mdx#extending-built-in-models

I didnt add the body parsing because i suppose in most cases you might want to use also the other params in the model so using an envelope would not be helpful.

[heitorlessa]

thanks a lot as always @risenberg-cyberark - As discussed, I'll commit these suggestions, and will try pushing the docs to your branch then merge. Failing that, I'll merge as-is, then send another PR with docs and suggestions implemented ;)

ETA: This Friday EOD

[heitorlessa]

Doc added - Merging