Add a typed ProjectionExpression constructor

[pomadchin]

This PR adds an extra ProjectionExpression constructor with a type parameter.

Let me know what you think about it! I know that it's a low-level API and we probably can't encourage users using it, but it can be really useful sometimes to hide some dirt under the table.

[CLAassistant]

All committers have signed the CLA.

[pomadchin]

BTW I noticed that https://github.com/zio/zio-dynamodb/tree/series/2.x/.idea is commited into the repo! Is it intended? (it def conflicts with my local settings and locally idea overwrites it)

[googley42]

So re $$ proposal - I think I would prefer the existing clean separation of High level and low level APIs - for instance in the High level API the use of .unsafeTo is actually "safe" in the scope of a ZIO Schema derived from the trait/case class - but is literally unsafe here for $$ as the field name and type are associated by hand

[googley42]

closing for reason mentioned in comment

[googley42]

Re-opened as I can see this will be useful for defining ProjectExpressions for enums that are non root - ATM there is no high level API functionality to cover this.