[transferring] Change transferring to no longer be a ParamSpecifier.

Instead it is a bit on ParamDecl and SILParameterInfo. I preserve the consuming
behavior by making it so that the type checker changes the ParamSpecifier to
ImplicitlyCopyableConsuming if we have a default param specifier and
transferring is set. NOTE: The user can never write ImplicitlyCopyableConsuming.

NOTE: I had to expand the amount of flags that can be stored in ParamDecl so I
stole bits from TypeRepr and added some logic for packing option bits into
TyRepr and DefaultValue.

rdar://121324715

lib/Serialization/ModuleFormat.h

@@ -58,7 +58,7 @@ const uint16_t SWIFTMODULE_VERSION_MAJOR = 0;
 /// describe what change you made. The content of this comment isn't important;
 /// it just ensures a conflict if two people change the module format.
 /// Don't worry about adhering to the 80-column limit for this line.
-const uint16_t SWIFTMODULE_VERSION_MINOR = 852; // SILFunctionType::ErasedIsolation
+const uint16_t SWIFTMODULE_VERSION_MINOR = 853; // transferring fixes
 
 /// A standard hash seed used for all string hashes in a serialized module.
 ///
@@ -359,7 +359,7 @@ enum class ParamDeclSpecifier : uint8_t {
   Consuming = 3,
   LegacyShared = 4,
   LegacyOwned = 5,
-  Transferring = 6,
+  ImplicitlyCopyableConsuming = 6,
 };
 using ParamDeclSpecifierField = BCFixed<3>;
 
@@ -402,6 +402,7 @@ enum class SILParameterDifferentiability : uint8_t {
 enum class SILParameterInfoFlags : uint8_t {
   NotDifferentiable = 0x1,
   Isolated = 0x2,
+  Transferring = 0x4,
 };
 
 using SILParameterInfoOptions = OptionSet<SILParameterInfoFlags>;
@@ -1605,6 +1606,7 @@ namespace decls_block {
     BCFixed<1>,              // isAutoClosure?
     BCFixed<1>,              // isIsolated?
     BCFixed<1>,              // isCompileTimeConst?
+    BCFixed<1>,              // isTransferring?
     DefaultArgumentField,    // default argument kind
     TypeIDField,             // default argument type
     ActorIsolationField,     // default argument isolation