API + Model: Add support for JSON schema constraints

Add the ability to constrain the return value of a model to be JSON.
Built using the JSON schema standard to define the properties of what
the model should return.

This feature should be more accurate than using GBNF/EBNF to yield
the same results due to the use of lmformatenforcer.

GBNF/EBNF will be added in a different commit/branch.

Signed-off-by: kingbri <bdashore3@proton.me>

common/sampling.py

@@ -118,6 +118,10 @@ class BaseSamplerRequest(BaseModel):
         default_factory=lambda: get_default_sampler_value("negative_prompt")
     )
 
+    json_schema: Optional[object] = Field(
+        default_factory=lambda: get_default_sampler_value("json_schema"),
+    )
+
     # Aliased variables
     typical: Optional[float] = Field(
         default_factory=lambda: get_default_sampler_value("typical", 1.0),
@@ -261,6 +265,7 @@ class BaseSamplerRequest(BaseModel):
             "mirostat_eta": self.mirostat_eta,
             "cfg_scale": self.cfg_scale,
             "negative_prompt": self.negative_prompt,
+            "json_schema": self.json_schema,
         }
 
         return {**gen_params, **kwargs}