LifetimeDependence: implement strict type checking

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LifetimeDependence: implement strict type checking

Rework the type checker to support completely checking lifetime dependence requirements. Don't let anything through without the feature being enabled and complete annotation or inference.

First, prevent lifetime dependencies from sneaking into source that does not enable LifetimeDependence. This is essential for controlling the scope of the feature.

Fixing this is disruptive because, ever since ~Escapable was introduced we have been declaring empty non-Escapable types without enabling LifetimeDependence. Such as:

  struct Implicit_Init_Nonescapable : ~Escapable {}

Fixes: rdar://145979187 ([nonescapable] diagnose implicit non-Escapable initializers as an error unless LifetimeDependence is enabled)

Various forms of unsupported 'inout' dependencies are now also caught by the type checker.

Second, disable lifetime dependency inferrence except in unambiguous cases and some implicitly generated cases.

Fixes: rdar://131176898 ([nonescapable] missing diagnostic for incorrectly inferred inherited dependence)

This is important to avoid source compatibility problems as inference rules change. They will change as the proposal goes through review.

This fixes various latent missing dependency bugs.

Disable experimental lifetime dependence inference. Unambiguous lifetime dependency candidates will still be inferred by default, without any frontend options. Ambiguous candidates will, however, no longer be inferred unless -Xfrontend -enable_experimental_lifetime_dependence_inference is enabled.

This all has to be done without breaking existing .swiftinterface files. So backward compatibility logic is maintained.

Examples of inference rules that are no longer enabled by default:

1. do not infer a dependency on non-Escapable 'self' for methods with more than zero parameters:

    extension NE: ~Escapable {
      /*@lifetime(self)*/ // ERROR: 'self' not inferred
      func method<Arg>(arg: Arg) -> NE { ... }
    }

2. Never infer a 'copy' dependency kind for explicit functions

    extension NE: ~Escapable {
      @lifetime(self) // ERROR: 'copy' not inferred
      func method() -> NE { ... }

      @lifetime(self) // ERROR: 'copy' not inferred
      var property : NE { /*@lifetime(self: newValue)*/ set { ... } }
    }

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@swift-ci test

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@swift-ci Please smoke test compiler performance

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@swift-ci benchmark

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@swift-ci Please Build Toolchain macOS Platform

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@swift-ci Please Test Source Compatibility Debug

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The only macOS test failure was the known spurious test failing the same spurious way: Interpreter/preconcurrency_conformances.swift

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@swift-ci smoke test macOS

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@swift-ci test

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@swift-ci smoke test