RFC: rename LambdaEnv -> Invocation

[armanbilge]

I think "invocation" is a more suitable:

• the event and context are relevant only during a specific invocation of the lambda function
• "env" is reminiscent of environment variables that have a different lifecycle. Also the concept became overloaded in our custom lambda runtime which is less than ideal.

I left deprecated aliases in place. Should be a pretty easy find-replace for downstreams.

[fredshonorio]

Having superficial experience with aws lambda (before feral existed) I like the new name better.

[bpholt]

Seems reasonable. Could we provide a Scalafix for the rewrite?

[armanbilge]

Could we provide a Scalafix for the rewrite?

Let me look into that :)

Update: this is a really great example!
typelevel/catbird@7992250

[armanbilge]

Will do a follow-up PR with scalafixes for this and some other changes. Thanks everyone!