- Follow-up on #817
### Unit tests
Adds tests for:
- LinkConnector
- LGraph
### Integration tests for LinkConnector
- Uses and configures a real graph + LGraph
- Avoids mocks
- User input is still mocked
- Performs actual tasks as would be called by LGraphCanvas
- A little verbose in places, but _many_ edge cases are caught by these
tests
- Updates UUIDv4 generator
- Adds a unique id & revision support to graphs
- `revision` to be incremented downstream (e.g. on save)
- `id` automatically assigned if not provided
* [Test] Revert custom name for test context
- Removes "lgTest", replaces with default "test"
* nit - Rename test extensions file
* Split test graphs out to separate file