Stac-pydantic

- Remove fields added by STAC API search extensions (100, rsmith013 & moradology)
- Add ExtendedSearch class with fields from STAC API search extensions (100, rsmith013 & moradology)
- Allow for non-ellipsis open temporal windows (103, moradology)
- Add the canonical and service-doc relation types (104, moradology)

- Add bbox validator to STAC search (95, geospatialjeff)
- Fix LandPage to make valid STAC 1.0 catalog (96, lossyrob)

- Add Collections model (81, moradology)
- Update to stac version 1.0.0 (86, moradology)
- Remove models for STAC spec extensions (86, moradology)
- Add conformsTo to LandingPage (90, moradology)

- Add id to landing page, making it a valid catalog (43, lossyrob)
- Make `item_assets` (item assets extension) a dictionary of assets (47, kylebarron)
- Add pre-commit to CI (48, kylebarron)
- Add a `Links` model with custom root type to represent a list of links (52)
- Move link related models to their own file (53)
- Add link factories for generating inferred links (55)
- Switch from relative to absolute imports (61)
- Serialize date type fields to `datetime.datetime` upon model creation (62)

- Remove enum restriction for asset roles (39).
- Remove enum restriction for band common name (40).

- Rename `proj` extension to `projection` (34).
- Remove `stac_extensions` enum requirement (35).