refactor!: connection approval

[jeffreyrainy]

Adjust the connection approval flow, which was changed in previous release. This puts back the ability to delay approval.

• The Connection Approval callback is now: public Action<ConnectionApprovalRequest, ConnectionApprovalResponse> ConnectionApprovalCallback;
• The ConnectionApprovalResponse goes from a struct to a class, and gets reference semantics.
• Client code doesn't allocate ConnectionApprovalResponse, they write to the response we allocate for them
• Client code can set the response .Pending member to true, to indicate it is still processing the approval and set .Pending to false, later, once it has decide to approve or reject the connection.

Changelog

Pending changes will come in a later commit.

Testing and Documentation

MultiClientConnectionApproval now tests both immediate and delayed approval.

[JesseOlmer]

The change to ConnectionApprovalResponse type, and the callback change from Func to Action are both breaking changes which should constitute a 2.0 rev of ngo. @ThusWroteNomad @lpmaurice is that on the table currently?

[0xFA11]

@JesseOlmer

The change to ConnectionApprovalResponse type, and the callback change from Func to Action are both breaking changes which should constitute a 2.0 rev of ngo. @ThusWroteNomad @lpmaurice is that on the table currently?

since we haven't released NGO 1.0 yet, this area (connection approval) was one of the exceptions post pre.9 that we said OK for API breaking changes — and since we already changed the API just a few weeks ago, making this modification before we fully release NGO 1.0 should be OK too.

not ideal but still better than leaving the door open for misuse after 1.0 release or leaving it as is right now and taking away the functionality of delaying approval result from devs.

[SamuelBellomo]

Tested with boss room and I confirm we can receive custom messages with this

[JesseOlmer]

lgtm