Pystac v2: Get tests/v1 passing

[jsignell]

I was just chatting with @ircwaves and he is down to help out with getting v1 tests passing on v2, so I figured we might need somewhere to coordinate work:

• ├── html
  │   └── test_html.py -> refactor: self href and self link handling #1659
• ├── posix_paths
  │   └── test_posix_paths.py -> test: enable posix path tests #1658
  ├── serialization
• │   ├── test_identify.py
• │   └── test_migrate.py
• ├── test_asset.py -> feat: V2 asset #1646
• ├── test_cache.py
• ├── test_catalog.py -> @ircwaves working V2 catalog test updates #1702
• ├── test_collection.py -> feat: V2 collection tests #1668
• ├── test_common_metadata.py
• ├── test_item_assets.py -> feat: V2 asset #1646
• ├── test_item_collection.py -> fix: V2 item collection #1709
• ├── test_item.py
• ├── test_layout.py
• ├── test_link.py -> @ircwaves working feat: V2 links updates #1693
• ├── test_pystac_client.py
• ├── test_stac_io.py
• ├── test_summaries.py -> @jsignell working on this
• ├── test_utils.py
• ├── test_version.py
• ├── test_writing.py
• ├── utils
  │   └── test_cases.py
  └── validation
• ├── test_schema_uri_map.py
• └── test_validate.py