[6.2] Bypass lifetime diagnostics in interfaces for copied arguments.

[atrick]

main PR: #81105

• LifetimeDependenceScopeFixup: cleanup for clarity
  (cherry picked from commit bb9e52c)

• [NFC] LifetimeDependenceUtils comment
  (cherry picked from commit 0603645)

• Fix LifetimeDependence attribute checking
  Handle parameters with no name: foo(_:T)

  (cherry picked from commit a7c9b6e)

• Fix LifetimeDependenceDiagnostics: handle mark_dependence_addr
  A small typo meant that scoped dependencies modeled with mark_dependence_addr
  were not diagnosed.

  (cherry picked from commit 92b2a85)

• Fix LifetimeDependenceDiagnostics: scoped dependence on a copy
  Diagnose a scoped dependence on an argument that inherits its lifetime as an
  error:

  @Lifetime(borrow arg)
  func reborrowSpan(_ arg: Span) -> Span { arg }

  @Lifetime(copy span)
  public func testBorrowInheritedArg(_ span: Span) -> Span {
  reborrowSpan(span) // expected-error {{lifetime-dependent value escapes its scope}}
  }

  Fixes: rdar://146319009 ([nonescapable] enforce borrow constraint narrowing of inherited lifetime)
  (cherry picked from commit 4f470a1)

• Add .swiftinterface tests to check backward compatibility.
  (cherry picked from commit 49a8770)

• Add _overrideLifetime to Span APIs
  The implementation previously took advantage of a missing diagnostic. They
  returned a borrowed Span with a dependency on a copied argument. This illegally
  promotes the dependency. This is what the author intended to do (the
  implementation was correct) but the compiler can't know that so the code needs
  to be explicit about overriding the lifetime.

  (cherry picked from commit e9d1128)

• Update tests for stricter diagnostics on borrowed argument lifetime
  (cherry picked from commit 4ef3b4f)

• Disable a test until SILGen supports borrowing getter + library evo
  rdar://150073405 ([SILGen] support synthesized _modify on top of borrowed
  getters with library evolution)

  (cherry picked from commit 78758da)

• Bypass lifetime diagnostics in interfaces for copied arguments.
  Briefly (April 2025), RawSpan._extracting, Span._extracting, and UTF8Span.span
  returned a borrowed value that depended on a copied argument. Continue to
  support those interfaces. The implementations were correct but needed an
  explicit _overrideLifetime.

  (cherry picked from commit 8a48cd9)

[atrick]

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