community[minor]: Unify Titan Takeoff Integrations and Adding Embedding Support (#18775)

**Community: Unify Titan Takeoff Integrations and Adding Embedding
Support**

 **Description:** 
Titan Takeoff no longer reflects this either of the integrations in the
community folder. The two integrations (TitanTakeoffPro and
TitanTakeoff) where causing confusion with clients, so have moved code
into one place and created an alias for backwards compatibility. Added
Takeoff Client python package to do the bulk of the work with the
requests, this is because this package is actively updated with new
versions of Takeoff. So this integration will be far more robust and
will not degrade as badly over time.

**Issue:**
Fixes bugs in the old Titan integrations and unified the code with added
unit test converge to avoid future problems.

**Dependencies:**
Added optional dependency takeoff-client, all imports still work without
dependency including the Titan Takeoff classes but just will fail on
initialisation if not pip installed takeoff-client

**Twitter**
@MeryemArik9

Thanks all :)

---------

Co-authored-by: Bagatur <baskaryan@gmail.com>
Co-authored-by: Bagatur <22008038+baskaryan@users.noreply.github.com>

libs/langchain/langchain/llms/__init__.py

@@ -469,9 +469,9 @@ def _import_titan_takeoff() -> Any:
 
 
 def _import_titan_takeoff_pro() -> Any:
-    from langchain_community.llms.titan_takeoff_pro import TitanTakeoffPro
+    from langchain_community.llms.titan_takeoff import TitanTakeoff
 
-    return TitanTakeoffPro
+    return TitanTakeoff
 
 
 def _import_together() -> Any:

libs/langchain/langchain/llms/titan_takeoff_pro.py

@@ -1,3 +1,3 @@
-from langchain_community.llms.titan_takeoff_pro import TitanTakeoffPro
+from langchain_community.llms.titan_takeoff import TitanTakeoff as TitanTakeoffPro
 
 __all__ = ["TitanTakeoffPro"]