FEAT: Federated connections

[tusharpandey13]

WIP

• Moved authentication server metadata discovery to a separate stateful class for use in both authentication and FC exchange methods; this maintains an in-memory cache of metadata.
• Added a getFCAT method with checks for existing FCATs and writeback to the session store.
• Moved encrypted cookie read and write logic to a dedicated storage layer, abstracting session store methods.
• Implemented FC exchange functionality.
• Created a class to handle FCAT serialization/deserialization, including cookie storage logic.
• Added logic to serialize/deserialize FCATs along with session data to the cookie store.
• Added a federatedConnectiontMap property.

Please see comments below

[tusharpandey13]

1. Authentication server metadata discovery is moved to a seperate stateful class since it is also used in FC exchange method.
2. nullish coalescing operator is used in favour of logical OR
3. getAudience() getter added
4. Added class members for FederatedConnections classs

[tusharpandey13]

Authentication server metadata discovery is moved here, this maintains an in-memory cache of the metadata, something that was maintained in the auth-client itself as a class member.
Since this is used in FC exchange function as well, de-coupled the implementation from auth client.

[tusharpandey13]

1. Simplified logic of various method by extracting repeated code.
2. Added getFCAT method with check for existing FCAT and writeback to session store.

[tusharpandey13]

Moved encrypted cookie read and write logic to this storage layer.
This also abstracts the sessionstore methods.

[tusharpandey13]

Performs FC exchange.
Only contains code releavant to exchange.

[tusharpandey13]

Deals with FCAT serialization/deserialization processes.
Contains low-level logic for how FCATs are stored in the cookie store.
Maintains a 2-level map of provider:audience:FCAT

[tusharpandey13]

Add logic to serialize/deserialize FCATs along with session data to cookie store.

[tusharpandey13]

Added federatedConnectiontMap prop.