import pydantic objects from the `_pydantic_compat` module (#17667)

This PR changes `from pydantic import BaseModel` to `from
synapse._pydantic_compat import BaseModel` (as well as `constr`,
`conbytes`, `conint`, `confloat`).

It allows `check_pydantic_models.py` to mock those pydantic objects only
in the synapse module, and not interfere with pydantic objects in
external dependencies.

This should solve the CI problems for #17144, which breaks because
`check_pydantic_models.py` patches pydantic models from
[scim2-models](https://scim2-models.readthedocs.io/).

/cc @DMRobertson @gotmax23
fixes #17659 


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1 files changed, 63 insertions, 1 deletions

diff --git a/synapse/_pydantic_compat.py b/synapse/_pydantic_compat.py

index a6ceeb04d2..f0eedf5c6d 100644
--- a/synapse/_pydantic_compat.py
+++ b/synapse/_pydantic_compat.py
@@ -19,6 +19,8 @@
 #
 #
 
+from typing import TYPE_CHECKING
+
 from packaging.version import Version
 
 try:
@@ -30,4 +32,64 @@ except ImportError:
 
 HAS_PYDANTIC_V2: bool = Version(pydantic_version).major == 2
 
-__all__ = ("HAS_PYDANTIC_V2",)
+if TYPE_CHECKING or HAS_PYDANTIC_V2:
+    from pydantic.v1 import (
+        BaseModel,
+        Extra,
+        Field,
+        MissingError,
+        PydanticValueError,
+        StrictBool,
+        StrictInt,
+        StrictStr,
+        ValidationError,
+        conbytes,
+        confloat,
+        conint,
+        constr,
+        parse_obj_as,
+        validator,
+    )
+    from pydantic.v1.error_wrappers import ErrorWrapper
+    from pydantic.v1.typing import get_args
+else:
+    from pydantic import (
+        BaseModel,
+        Extra,
+        Field,
+        MissingError,
+        PydanticValueError,
+        StrictBool,
+        StrictInt,
+        StrictStr,
+        ValidationError,
+        conbytes,
+        confloat,
+        conint,
+        constr,
+        parse_obj_as,
+        validator,
+    )
+    from pydantic.error_wrappers import ErrorWrapper
+    from pydantic.typing import get_args
+
+__all__ = (
+    "HAS_PYDANTIC_V2",
+    "BaseModel",
+    "constr",
+    "conbytes",
+    "conint",
+    "confloat",
+    "ErrorWrapper",
+    "Extra",
+    "Field",
+    "get_args",
+    "MissingError",
+    "parse_obj_as",
+    "PydanticValueError",
+    "StrictBool",
+    "StrictInt",
+    "StrictStr",
+    "ValidationError",
+    "validator",
+)