Introduces saturated truncate instructions to Global ISel:
G_TRUNC_SSAT_S, G_TRUNC_SSAT_U, G_TRUNC_USAT_U. These were previously
introduced to SDAG to reduce redundant code.

The patch only initially introduces the instruction, a later patch will
follow to add combines and legalization for each instruction.

Add per-property has<Prop>/set<Prop>/reset<Prop> functions to
MachineFunctionProperties.

We can use *Set::insert_range to collapse:

  for (auto Elem : Range)
    Set.insert(E);

down to:

  Set.insert_range(Range);

DenseSet, SmallPtrSet, SmallSet, SetVector, and StringSet recently
gained C++23-style insert_range.  This patch uses insert_range in
conjunction with llvm::{predecessors,successors} and
MachineBasicBlock::{predecessors,successors}.

DenseSet, SmallPtrSet, SmallSet, SetVector, and StringSet recently
gained C++23-style insert_range.  This patch replaces:

  Dest.insert(Src.begin(), Src.end());

with:

  Dest.insert_range(Src);

This patch does not touch custom begin like succ_begin for now.

Most places that call Intrinsic::getAttributes() are only interested in
the function attributes, so add a separate function for that.

The motivation for this is that I'd like to add the ability to specify
range attributes on intrinsics, which requires knowing the function
type. This avoids needing to know the type for most attribute queries.

From #106446, this adds a variant of getVectorIdxTy that returns an LLT.
Many uses only look at the width, so a getVectorIdxWidth was added as
the common base.

I'm not sure of a good example to test the "does not fully support"
case.