[CIR] Add tons of function infra, plus a handful of attributes (#179811)

This patch puts together a lot more of the CIR infrastructure for
function attributes, plus adds a bunch of 'TODO' messages for areas that
have been skipped.

Along the way, we also implement 8 attributes in some way: -Convergent
gets a little more work, to make the `noconvergent` C attribute have an
effect

-optsize/minsize are implemented, sourced from the command line

-nobuiltin is a call-only attribute that tells not to replace the
individual call with a builtin. This is a touch confusing, since
no-builtins is an attribute that means "don't replace anything in the
body of this function with builtins (from this list)". The spelling
confusion is existing, and it seems that changing the names away from
LLVM would be confusing.

-save_reg_params & zero_call_used_regs are boht pretty simple registers

-temp-func-name just passes a string to LLVM, consistent with existing
implementation.

-default-func-attrs is a difficult one. It takes command line arguments
and passes them as LLVM-IR attributes directly on functions/calls. In
the dialect, we are capturing these in their own attribute to pass them
on correctly. However, this is one we cannot recover from LLVM-IR for
obvious reasons, so we instead choose to let the 'passthrough' mechanism
work for those.