[region-isolation] Make fields of global actor guarded types that are non-Sendable be considered as actor isolated.

[gottesmm]

This PR has a few commits in it that ensure that we treat global actor isolated types (which are considered non-Sendable) as actor isolated when performing region isolation checking.

Specifically:

1. The first commit changes how we represent transferring results at the SIL level. Instead of using a bit in the SILFunctionType (like we are doing in AnyFunctionType since AnyFunctionType), we instead just propagate the bit in TypeLowering to all SILResultInfo. I put in a verification check that if any SILResultInfo are transferring, then all must be transferring. In the fullness of time this will ensure that at the SIL level we will be a bee to easily handle results with different transferring semantics. It also made it so that I could actually write SIL level tests with sil_transferring (the previous implementation relied upon the AST level printer by mistake which caused @owned/@guaranteed to be parsed, but ignored).
2. The second commit simplifies how we emit diagnostics in TransferNonTransferrable to match what UseAfterTransfer does. Specifically, previously we would have a machine that would produce UseDiagnosticInfo via inference and then a second machine that would consume those and emit a diagnostic. This made it heavy to add new diagnostics (too much code to touch) and hard to track down why a diagnostic was emitted. Instead we now use an emitter helper that in the inference code just immediately emits the error making it easy to diagnose why the error happened using swift-diagnostics-assert-on-error.
3. This is the meat commit where I ensure that we handle structs/enums that are main actor isolated correctly.

rdar://123488540

[gottesmm]

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