Custom document IDs

[a-Leong]

Related: #234

Is your feature request related to a problem? Please describe. Currently there is no way to use a custom doc ID when creating a new row. My project utilizes custom doc IDs in some cases, and I would like to be able to handle these in Firetable.

Describe the solution you'd like When creating a new row, an option provided to use a custom ID instead of the default generated ID.

[tv42]

I have a project that uses a DNS domain name as a key in one place, to ensure only one owner can claim a domain successfully. That's the only mechanism I know of in Firestore to ensure uniqueness. I'm sure others have similar needs.

[notsidney]

This was released in v2.2.0