Support `clang-repl` (C++ repl)

[PowerUser64]

Currently, Conjure does not support evaluating C++ code. If Conjure were to add support for clang-repl, then it would be able to evaluate C++ code.

Prerequisites:

• [ ] C++ sandbox file (eg. like this one), containing expressions that Conjure should be able to evaluate.
  • This file should try to contain examples of edge cases that Conjure would need to walk up the AST in order to evaluate without causing errors.