[lldb][SBType] GetBasicType to unwrap canonical type (#149112)
`SBType::GetBasicType` fails on typedefs to primitive types. The docs
for `GetBasicType` state:
```
Returns the BasicType value that is most appropriate to this type
```
But, e.g., for `uint64_t` this would currently return
`eBasicTypeInvalid`.
`TypeSystemClang::GetBasicTypeEnumeration` (which is what
`SBType::GetBasicType` uses) doesn't see through typedefs. Inside LLDB
we almost always call `GetBasicTypeEnumeration` on the canonical type.
In the cases we don't I suspect those were just subtle bugs. This patch
gets the canonical type inside of `GetBasicTypeEnumeration` instead.
rdar://155829208