Add Taipy-specific and hidden parameters to navigate()

[FabienLelaquais]

Description

We had a request to allow a Taipy application to query another Taipy application page, potentially served by another Taipy GUI application.
This can be done using the params parameter to navigate() but then the URL is complemented with the query string that the requestee is willing to hide, for security reasons.

Solution Proposed

navigate() will be added a hidden_params parameter, with the same semantics as for params: a dictionary that holds string keys and serializable value.
The on_navigate callback will receive an additional hidden_params parameter, set to a dictionary that reflects what was provided in the call to navigate().

Impact of Solution

Those parameters are encoded in the GET query header, so no POST is mandatory.
In order not to unintendedly overwrite the original headers configuration, each hidden parameter is propagated with an internal (and undocumented) prefix that identifies them before they're encoded in the query header.
Taipy GUI will decypher all that before on_navigate is triggered.

Acceptance Criteria

• If applicable, a new demo code is provided to show the new feature in action.
• Integration tests exhibiting how the functionality works are added.
• Any new code is covered by a unit tested.
• Check code coverage is at least 90%.
• Related issue(s) in taipy-doc are created for documentation and Release Notes are updated.

Code of Conduct

• I have checked the existing issues.
• I am willing to work on this issue (optional)