Allow lock code usage without an integration

Allow smart lock code generation, management and usage without any lock integration enabled, i.e. visibility of the codes on reservations, usage of the shortcode in messages, etc. And, add the generated lock code to the webhook and API payloads.

I have Yale smart locks (Z-Wave) that are intentionally not cloud-connected, but which are part of my Home Assistant controlled Z-Wave network. I currently manage my guest lock codes using the Hospitable iCal feed, by letting a Home Assistant automation parse out the last 4 digits of the guest's phone number and then taking it from there. This works well enough, but this feature request would improve things for me as follows:

1. My operations team could see the lock code under the reservation UI of Hospitable, improving manual guest communication.

2. My integration could use pre-parse lock codes from Hospitable, including random generated codes, vs. having to parse them out of the phone number.

3. My integration could utilize webhooks and/or the API to more deliberately interface with lock code management, vs. having to rely on the calendar phone number parsing for this.

My use case aside, I could also see this feature benefitting a "sneaker-net" sub-group of users:

1. They don't have smart locks -- i.e. they use lock boxes or manual keypads -- but would like to use rotating codes on these devices.

2. They do use smart locks, but can't/don't want to connect them via integration, thus they'd need to provision them manually into the locks via local app, physical access, etc.