Fix compiler concurrency issues

[rablador]

Find all occurrences of types that are being shared across actor boundaries. For each type, determine if they are sendable as is or if they need to be refactored to be sendable.

The swift compiler should guide us to find the types that are being sent, when enforcing strict concurrency checks.

This ticket fixes issues reported up to checking level "targeted".

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This change is 

[linear]

IOS-828 Fix compiler concurrency issues for level 'targeted'

[rablador]

Reviewable status: 0 of 59 files reviewed, 1 unresolved discussion

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ios/PacketTunnelCore/Actor/Task+Duration.swift line 64 at r2 (raw file):

            }
        } onCancel: {
            timer.cancel()

This timer actually yields a warning, but I don't know how to make DispatchSourceTimer sendable since it's a system provided protocol. sleepUsingContinuousClock() will be deprecated in next iOS version, so perhaps we can leave it as is.

[rablador]

Will put this PR on hold since compiler (xcode 15.0.1) on CI reports errors not on later xcode versions (16 and onwards).

Reviewable status: 0 of 59 files reviewed, 1 unresolved discussion