[Entities-Routes] It is possible to save updates for Route if required field is empty in JSON format.

### EPAM AI DIAL Admin version

Admin: [FE]0.17.0-dev.79 [BE]0.17.0-dev.7

### How to reproduce

DEV environment

1. Navigate to Entities -> Routes
2. Open any Route with entered and saved 'Upstream Endpoints' field.
3. Delete value from 'Upstream Endpoints' field.
4. Verify 'Save' button. **Expected:** the button is disabled.
5. Switch to the JSON editor.
6. Delete value for "upstreams"
7. Verify 'Save' button.
8. Repeat the same steps for Entities->Applications-> App Routes
9. Repeat the same steps for Builders->Application Runners -> App Routes
10. Verify the same for 'methods' field.

### Actual result

'Save' button is not disabled.
It is possible to update Route without filling required 'Upstream Endpoints' and 'Methods'field.

### Expected result

If "upstreams", 'methods' are empty or absent in JSON backend should return a proper error message.
The same validation should be applied for:
Entities->Applications-> App Routes
Builders->Application Runners -> App Routes

### Additional information

_No response_

### Confidential information

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