Until now, `builtin.unrealized_conversion_cast` ops could not be inlined
by the Inliner pass.

These are identified by misc-include-cleaner.  I've filtered out those
that break builds.  Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.

The proper layering here is that Inliner depends on InlinerUtils, and
not the other way round. Maybe it's time to give InliningUtils a less
terrible file name.

Current inliner disables inlining when the caller is in a region with
single block trait, while the callee function contains multiple blocks.
the SingleBlock trait is used in operations such as do/while loop, for
example fir.do_loop, fir.iterate_while and fir.if. Typically, calls within
loops are good candidates for inlining. However, functions with multiple
blocks are also common. for example, any function with "if () then
return" will result in multiple blocks in MLIR.

This change gives the flexibility of a customized inliner to handle such
cases.
doClone: clones instructions and other information from the callee
function into the caller function. .
canHandleMultipleBlocks: checks if functions with multiple blocks can be
inlined into a region with the SingleBlock trait.

The default behavior of the inliner remains unchanged.

---------

Co-authored-by: jeanPerier <jean.perier.polytechnique@gmail.com>
Co-authored-by: Mehdi Amini <joker.eph@gmail.com>

We can use *Set::insert_range to collapse:

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

down to:

  Set.insert_range(Range);

In some cases, we can further fold that into the set declaration.

When inlining a `callee` with a call site debug location, the inlining
infrastructure was trivially combining the `callee` and the `caller`
locations, forming a "tree" of call stacks. Because of this, the remarks
were printing an incomplete inlining stack.

This commit handles this case and appends the `caller` location at the
end of the `callee`'s stack, extending the chain.

alternate option to https://github.com/llvm/llvm-project/pull/122615