Move choose_generation_strategy from ax.preview.modelbridge to ax.preview.api

Summary:
We need to move the new dispatch logic out of ax.preview in preparation for promoting the api module out of ax.preview. There are a number of things to take into consideration while making this move, including:
* Keeping the api module a top level import and not importing it from anywhere else in the Ax codebase
* Continuing to allow choose_generation_strategy to accept a GenerationStrategyConfig rather than all the options and flags individually

After some consideration, the most natural place for this is inside the api.utils module. This is where the other functions that consume Configs and produce Ax objects live.

Differential Revision: D70732507

Author: mpolson64

ax/preview/api/client.py

@@ -45,12 +45,12 @@
 from ax.preview.api.protocols.metric import IMetric
 from ax.preview.api.protocols.runner import IRunner
 from ax.preview.api.types import TOutcome, TParameterization
+from ax.preview.api.utils.generation_strategy_dispatch import choose_generation_strategy
 from ax.preview.api.utils.instantiation.from_config import experiment_from_config
 from ax.preview.api.utils.instantiation.from_string import (
     optimization_config_from_string,
 )
 from ax.preview.api.utils.storage import db_settings_from_storage_config
-from ax.preview.modelbridge.dispatch_utils import choose_generation_strategy
 from ax.service.scheduler import Scheduler, SchedulerOptions
 from ax.service.utils.best_point_mixin import BestPointMixin
 from ax.service.utils.with_db_settings_base import WithDBSettingsBase

ax/preview/modelbridge/dispatch_utils.py ax/preview/api/utils/generation_strategy_dispatch.py

@@ -4,7 +4,8 @@
 # This source code is licensed under the MIT license found in the
 # LICENSE file in the root directory of this source tree.
 
-# pyre-unsafe
+# pyre-strict
+
 
 import torch
 from ax.core.trial_status import TrialStatus
@@ -131,8 +132,9 @@ def _get_mbm_node(
 def choose_generation_strategy(
     gs_config: GenerationStrategyConfig,
 ) -> GenerationStrategy:
-    """Choose a generation strategy based on the properties of the experiment
-    and the inputs provided in ``gs_config``.
+    """
+    Choose a generation strategy based on the properties of the experiment and the
+    inputs provided in ``gs_config``.
 
     NOTE: The behavior of this function is subject to change. It will be updated to
     produce best general purpose generation strategies based on benchmarking results.

ax/preview/modelbridge/tests/test_preview_dispatch_utils.py ax/preview/api/utils/tests/test_generation_strategy_dispatch.py

@@ -12,7 +12,7 @@
 from ax.modelbridge.registry import Generators
 from ax.models.torch.botorch_modular.surrogate import ModelConfig, SurrogateSpec
 from ax.preview.api.configs import GenerationMethod, GenerationStrategyConfig
-from ax.preview.modelbridge.dispatch_utils import choose_generation_strategy
+from ax.preview.api.utils.generation_strategy_dispatch import choose_generation_strategy
 from ax.utils.common.testutils import TestCase
 from ax.utils.testing.core_stubs import (
     get_branin_experiment,