Implement operators `<=` and `>=` to explicitly check the comparison
results to be `cmpLessThan` or `cmpEqual` instead of negating the result
of `operators<`.

Fixes #85947

…ror() [NFC]

This patch removes all of the Set.* methods from Status.

This cleanup is part of a series of patches that make it harder use the
anti-pattern of keeping a long-lives Status object around and updating
it while dropping any errors it contains on the floor.

This patch is largely NFC, the more interesting next steps this enables
is to:
1. remove Status.Clear()
2. assert that Status::operator=() never overwrites an error
3. remove Status::operator=()

Note that step (2) will bring 90% of the benefits for users, and step
(3) will dramatically clean up the error handling code in various
places. In the end my goal is to convert all APIs that are of the form

`    ResultTy DoFoo(Status& error)
`
to

`    llvm::Expected<ResultTy> DoFoo()
`
How to read this patch?

The interesting changes are in Status.h and Status.cpp, all other
changes are mostly

` perl -pi -e 's/\.SetErrorString/ = Status::FromErrorString/g' $(git
grep -l SetErrorString lldb/source)
`
plus the occasional manual cleanup.

The check that max_bit_pos == sign_bit_pos conflicts with the check that
sign_bit_pos < max_bit_pos in the block surrounding it.

Originally found by cppcheck - 
lldb/source/Utility/Scalar.cpp:756:23: warning: Opposite inner 'if'
condition leads to a dead code block. [oppositeInnerCondition]

Fixes #85985

It was aligning the byte size down. Now it aligns up. This manifested
itself as SBTypeStaticField::GetConstantValue returning a zero-sized
value for `bool` fields (because clang represents bool as a 1-bit
value).

I've changed the code for float Scalars as well, although I'm not aware
of floating point values that are not multiples of 8 bits.

This adds the ability to create a Scalar from an APFloat, and to create
an APFloat from an APSInt or another APFloat.

This function always expects the pointer to be valid, a reference seems
more appropriate.

In preparation for removing the `#include "llvm/ADT/StringExtras.h"`
from the header to source file of `llvm/Support/Error.h`, first add in
all the missing includes that were previously included transitively
through this header.

This is fixing all files missed in b0abd4893fa1, 39d8e6e22cd1, and
a11efd49266f.

Differential Revision: https://reviews.llvm.org/D154775

Note that those functions on the left hand side are soft-deprecated in
favor of those on the right hand side:

  getMinSignedBits -> getSignificantBits
  getNullValue     -> getZero
  isNullValue      -> isZero
  isOneValue       -> isOne

This renames the primary methods for creating a zero value to `getZero`
instead of `getNullValue` and renames predicates like `isAllOnesValue`
to simply `isAllOnes`.  This achieves two things:

1) This starts standardizing predicates across the LLVM codebase,
   following (in this case) ConstantInt.  The word "Value" doesn't
   convey anything of merit, and is missing in some of the other things.

2) Calling an integer "null" doesn't make any sense.  The original sin
   here is mine and I've regretted it for years.  This moves us to calling
   it "zero" instead, which is correct!

APInt is widely used and I don't think anyone is keen to take massive source
breakage on anything so core, at least not all in one go.  As such, this
doesn't actually delete any entrypoints, it "soft deprecates" them with a
comment.

Included in this patch are changes to a bunch of the codebase, but there are
more.  We should normalize SelectionDAG and other APIs as well, which would
make the API change more mechanical.

Differential Revision: https://reviews.llvm.org/D109483