Add data-driven TunnelSettingsUpdate type and method for atomically applying them...

[acb-mv]

modify Preferences{Interactor,ViewController} to use these.

This means that for each preferences change, the tunnel gets recreated only once. It also gives us a data-driven type for modelling changes to the preferences, factoring code out of TunnelManager into a self-contained type.

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This change is 

[linear]

IOS-510 Deduplicate tunnel manager changes from Preferences view model changes

[rablador]

Reviewed 5 of 5 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @acb-mv)

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ios/MullvadVPN/View controllers/Preferences/PreferencesInteractor.swift line 43 at r1 (raw file):

    }

    func setDNSSettings(_ newDNSSettings: DNSSettings, completion: (() -> Void)? = nil) {

Why do we keep this one around?

[buggmagnet]

Asides from the changes @rablador mentioned, this looks good.

2 things that don't appear in this PR but could be fixed here

• ⚠️ Line Length Violation: Line should be 120 characters or less; currently it has 154 characters (line_length) inPreferencesViewController:166
• ⚠️ Function Body Length Violation: Function body should span 50 lines or less excluding comments and whitespace: currently spans 54 lines (function_body_length) in PreferencesViewController:115

For the later one, we can just issue a // swiftlint:disable:next function_body_length directive

Reviewed 5 of 5 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @rablador)

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ios/MullvadVPN/View controllers/Preferences/PreferencesInteractor.swift line 43 at r1 (raw file):

Previously, rablador (Jon Petersson) wrote…

Why do we keep this one around?

Agreed, it looks like we can get rid of it

[acb-mv]

Reviewable status: 4 of 6 files reviewed, 1 unresolved discussion (waiting on @buggmagnet and @rablador)

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ios/MullvadVPN/View controllers/Preferences/PreferencesInteractor.swift line 43 at r1 (raw file):

Previously, buggmagnet wrote…

Agreed, it looks like we can get rid of it

It is my plan to replace other setmethods with updateSettingsbefore the PR gets promoted from draft.

[buggmagnet]

Reviewed 8 of 8 files at r2, all commit messages.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @acb-mv and @rablador)

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ios/MullvadVPNTests/MullvadSettings/TunnelSettingsUpdateTests.swift line 15 at r2 (raw file):

final class TunnelSettingsUpdateTests: XCTestCase {
    override func setUpWithError() throws {

nit
If we don't intend to use those, we can remove them

[acb-mv]

Reviewable status: 8 of 9 files reviewed, 1 unresolved discussion (waiting on @buggmagnet and @rablador)

[rablador]

Reviewed 7 of 8 files at r2, 1 of 1 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved

[buggmagnet]

Reviewed 1 of 1 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved