[CIR] Add inline function attributes (#162866)
Unlike the incubator, this adds the inline attribute directly to FuncOp
instead of adding the ExtraFnAttr dict.
This adds three new optional keywords to CIR: inline_always,
inline_never and inline_hint. Just like in OGCG -O0 implies inline_never
on functions withoutt the C++ `inline` keyword and no other
inlining-related attribute.
This patch also adapts all tests that use functions so they account for
LLVM attributes being attached now.
