LSPS2 - Tracking Issue

This is a tracking issue for a minimum viable implementation of the LSPS2 specification.
Greenlight will only implement the client-side and assume the LSPS trusts client flow.

**Prerequisites**
- [ ] Discovery of LSP-servers (See [PR 144](https://github.com/Blockstream/greenlight/pull/244))

**Implementation**
- [ ] lsps2.get_versions (See [PR 260](https://github.com/Blockstream/greenlight/pull/260))
- [ ] lsps2.get_info (See [PR 260](https://github.com/Blockstream/greenlight/pull/260))
- [ ] lsps2.buy (See [PR 260](https://github.com/Blockstream/greenlight/pull/260))
- [ ] First invoice generation using the scid received from lsps.buy
- [ ] Claiming the first payment
- [ ] Stop execution on Client trusts LSPS flow by default.
- [ ] Create warning if LSP closes channels to early

**Others**
- [ ] Cross implementation testing
- [ ] Documentation