[Bug]: Improve Logging for validation failure in HotReload

[abhishekkumams]

What happened?

For many scenarios, validation failure messages are not useful This needs to be improved.
for example:

1. using invalid connection string.
2. using an incorrect source for entity.

All the above just give a generic message showing: Unable to hot reload configuration file due to One or more errors occurred.
This message is not very useful in debugging.

Version

1.3.13-rc

What database are you using?

Azure SQL

What hosting model are you using?

Local (including CLI)

Which API approach are you accessing DAB through?

No response

Relevant log output

Code of Conduct

• I agree to follow this project's Code of Conduct

[sezal98]

We should put some context in the message saying that the last known config is being used for rendering the DAB engine if the validation fails.