Add support for LLVM 19

[jabraham17]

Adds support to use Chapel with LLVM 19

Testing:

• [x] build with gcc 7.5 on linux64 without CHPL_DEVELOPER
• [x] build with gcc 7.5 on linux64 with CHPL_DEVELOPER
• [x] build with clang 14 on MacOS M1
• [x] paratest (x86)
• [x] paratest with gasnet (x86)
• [x] paratest with --verify (x86)
• [x] start_test test/llvm/abi/aarch64/ on ARM64
• [x] start_test test/gpu/native with cuda 12
• [x] start_test test/gpu/native with cuda 12 with OFI
• [x] spot checked cuda 11

[Reviewed by @mppf]