Implement admin_addTrustedPeer rpc endpoint

[richardgreg]

Fixes #7811

Changes

1. Added ITrustedNodesManager Interface:
   Created a new ITrustedNodesManager interface to handle trusted nodes. This interface is similar to IStaticNodesManager but for trusted nodes. It provides methods InitAsync(), AddAsync(), RemoveAsync(), IsTrusted(), and exposes Nodes.

2. Implemented TrustedNodesManager Class:
   Implemented TrustedNodesManager, which reads/writes a trusted nodes file and manages a list of trusted nodes. It also implements INodeSource (or inherits from ITrustedNodesManager : INodeSource) so it can be used by CompositeNodeSource.

3. Added IsTrusted Property to Node:
   Modified the Node class used by the networking code to include a public bool IsTrusted { get; set; } property. This allows peers to reflect if they originate from trusted nodes.

4. Integrated TrustedNodesManager into PeerPool:
   Passed an ITrustedNodesManager instance into the PeerPool constructor and updated the peer creation logic (CreateNew methods) to mark nodes as trusted if they come from the trusted nodes manager.

5. Updated InitializeNetwork to Include TrustedNodesManager:
   Created and initialized TrustedNodesManager inside InitializeNetwork.cs, added it to CompositeNodeSource so that trusted nodes are considered in the node discovery pipeline, and passed it to PeerPool.

6. Updated IApiWithNetwork and IInitConfig:

Extended IApiWithNetwork interface to have a ITrustedNodesManager? TrustedNodesManager { get; set; } property (if needed).
Added a TrustedNodesPath property to IInitConfig and InitConfig to define the file path for trusted nodes.
Modified AdminRpcModule Constructor:
Updated the AdminRpcModule constructor to require an ITrustedNodesManager and implemented the admin_addTrustedPeer method using the trusted nodes manager and peer pool.

1. Updated Tests:
   Adjusted existing tests to provide an ITrustedNodesManager mock where needed. Added a new test (Test_admin_addTrustedPeer) to ensure admin_addTrustedPeer works correctly.

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