Not all containers have 8-byte alignment, so if we want to avoid lots of
manual logic for calculating container alignment on a case-by-case
basis, we must calculate alignment from the member variables before the
Class nodes have been replaced by Container nodes.
Types within containers were previously named TODO. This sorts it out so
they're named as their most resolved type. The current implementation
skips Typedef names.
When we were previously removing allocators, we were only able to work
with containers whose allocators appeared as their last template
parameter.
Now we can replace allocators in the middle of a parameter list.
This fixes tests for folly::sorted_vector_set.
Previously we had an `R"(` string in `OITraceCode.cpp` which allowed us
to include the file as a string. Instead, keep `OITraceCode.cpp` a fully
formed C++ file and utilise the build system to turn it into a string.
This will be used for more header files that are needed both as valid
headers and as strings for JIT compilation in the Typed TreeBuilder
work.