feat: [WIP] implement chat endpoint switch

[gaurarpit]

Purpose

• Implement capability to switch endpoint to custom or byod based on env config to give flexibility to users for their needs.
• Resolves #650

Does this introduce a breaking change?

• [ ] Yes
• [x] No

How to Test

• Test the code

poetry run pytest -m "not azure and not functional"      
poetry run pytest -m "functional"      
poetry run pytest -m "not azure"      

What to Check

Verify that the following are valid

• ...

Other Information

[github-actions[bot]]

Coverage Report •

File	Stmts	Miss	Cover	Missing
code
create_app.py	137	3	97%	203, 208, 331
code/backend/batch/utilities/helpers
env_helper.py	137	10	92%	228, 233–234, 237–239, 251, 255–257
code/backend/batch/utilities/helpers/config
conversation_flow.py	4	0	100%
TOTAL	2473	672	72%

Tests	Skipped	Failures	Errors	Time
212	0 :zzz:	0 :x:	0 :fire:	11.966s :stopwatch:

[cecheta]

I think this should be marked as a breaking change

[ross-p-smith]

I think this should be marked as a breaking change

Because this is a breaking change - I think we link to a new page from this link A backend that mimics the [On Your Data] flow, with the ability to switch to a custom backend. This could then document what these two endpoints do

[gaurarpit]

I think this should be marked as a breaking change

Because this is a breaking change - I think we link to a new page from this link A backend that mimics the [On Your Data] flow, with the ability to switch to a custom backend. This could then document what these two endpoints do

That's a very good suggestion. Will get something updated on the documentation today.