Sans

- Fix `sans.ClientType` and `sans.AsyncClientType` not being available during type analysis

- Fix a TypeError with `sans.prepare_and_execute`

- Added `sans.Command`, and improved some handling regarding private commands
- Improved typehinting for `sans.Client` and associated functions
- Exposed `sans.ClientType` and `sans.AsyncClientType` as typehint-only types for typehinting purposes
- Both are implemented at runtime via [typing.NewType](https://docs.python.org/3/library/typing.html#newtype)

- Fixes `response.raise_for_status()` erroring out (incorrectly), and properly attaches parent exception info to the new exception

- Loosen some requirements
- Fix XML iterators yielding the wrong element depth
- Remove LXML iterators due to being slower

- Bumps httpx version
- Fix an issue where queries were deliminated via `%2B` rather than `+`
- `utils.prepare_and_execute` now raises on status codes other than 2xx