Fix crash on showing alert for in-app purchase

[mojganii]

This pr fixes the crash problem in showing alert for adding more time.

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This change is 

[linear]

IOS-1028 Failing to display the aciton sheet on iPad

[rablador]

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @mojganii)

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ios/MullvadVPN/Extensions/UIAlertController+InAppPurchase.swift line 29 at r1 (raw file):

        )
        actionSheet.overrideUserInterfaceStyle = .dark
        actionSheet.view.tintColor = UIColor(red: 0.0, green: 0.59, blue: 1.0, alpha: 1)

We're using the same color in custom lists, right? If so, I think we should put it in the UIColor extensions.

[mojganii]

Reviewable status: 0 of 3 files reviewed, 1 unresolved discussion (waiting on @rablador)

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ios/MullvadVPN/Extensions/UIAlertController+InAppPurchase.swift line 29 at r1 (raw file):

Previously, rablador (Jon Petersson) wrote…

We're using the same color in custom lists, right? If so, I think we should put it in the UIColor extensions.

yes, we do. let's do that then

[SteffenErn]

Reviewed 3 of 3 files at r2, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @rablador)

[acb-mv]

Reviewed all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @rablador)

[rablador]

Reviewed 3 of 3 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved