[IR] Declare command line options in TableGen (#233195)
Move the IR options that code with an LLVMContext reads into IROptions.
-disable-auto-upgrade-debug-info and -disable-i2p-p2i-opt become
-auto-upgrade-debug-info and -i2p-p2i-opt, keeping the old spellings as
aliases (with a TODO for removal).
llvm/unittests/IR/LibraryOptionsContextTest.cpp no longer depends on
InstCombine (a makeshift before LLVMCore is ported)
LLM-aided
