3806: lower bool literal value r=flodiebold a=JoshMcguigan
Following up on #3805, this PR adds the literal value to `ast::LiteralKind` so when we lower we can use the actual value from the source code rather than the default value for the type. Ultimately I plan to use this for exhaustiveness checking in #3706.
I didn't include this in the previous PR because I wasn't sure if it made sense to add this information to `ast::LiteralKind` or provide some other mechanism to get this from `ast::Literal`.
For now I've only implemented this for boolean literals, but I think it could be easily extended to other types. A possible exception to this are string literals, since we may not want to clone around an owned string to hold onto in `ast::LiteralKind`, and it'd be nice to avoid adding a generic lifetime as well. Perhaps we won't ever care about the actual value of a string literal?
Co-authored-by: Josh Mcguigan <joshmcg88@gmail.com>