Use the `Base` type alias from
https://github.com/llvm/llvm-project/pull/158433.

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.

See https://github.com/llvm/llvm-project/pull/147168 for more info.

This patch deletes `vector.matrix_multiply` and `vector.flat_transpose`,
which are thin wrappers around the corresponding LLVM intrinsics:
  - `llvm.intr.matrix.multiply`
  - `llvm.intr.matrix.transpose`

These Vector dialect ops did not provide additional semantics or
abstraction beyond the LLVM intrinsics. Their removal simplifies the
lowering pipeline without losing any functionality.

The lowering chains:
- `vector.contract` → `vector.matrix_multiply` →
`llvm.intr.matrix.multiply`
- `vector.transpose` → `vector.flat_transpose` →
`llvm.intr.matrix.transpose`

are now replaced with:
  - `vector.contract` → `llvm.intr.matrix.multiply`
  - `vector.transpose` → `llvm.intr.matrix.transpose`

This was accomplished by directly replacing:
  - `vector::MatrixMultiplyOp` with `LLVM::MatrixMultiplyOp`
  - `vector::FlatTransposeOp` with `LLVM::MatrixTransposeOp`

Note: To avoid a build-time dependency from `Vector` to `LLVM`,
relevant transformations are moved from "Vector/Transforms" to
`Conversion/VectorToLLVM`.

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 `VectorTransformsOptions` on the `ConvertVectorToLLVMPass` is
currently represented as a struct, which makes it not serialisable. This
means a pass pipeline that contains this pass cannot be represented as
textual form, which breaks reproducer generation and options such as
`--dump-pass-pipeline`.

This PR expands the `VectorTransformsOptions` struct into the two
options that are actually used by the Pass' patterns:
`vector-contract-lowering` and `vector-transpose-lowering` . The other
options present in VectorTransformOptions are not used by any patterns
in this pass.

Additionally, I have changed some interfaces to only take these specific
options over the full options struct as, again, the vector contract and
transpose lowering patterns only need one of their respective options.

Finally, I have added a simple lit test that just prints the pass
pipeline using `--dump-pass-pipeline` to ensure the options on this pass
remain serialisable.

Fixes #129046

This PR continues with the introduction of poison as initialization
vector, in this particular case, in LowerVectorBitCast,
LowerVectorBroadcast and LowerVectorTranspose.

This PR adds a folder for `vector.extract(ub.poison) -> ub.poison`. It
also replaces `create` with `createOrFold` insert/extract ops in vector
unroll and transpose lowering patterns to trigger the poison foldings
introduced recently.

This patch is part of a project to move the Presburger library into
LLVM.

Splits `TransposeOpLowering` into two patterns:
1. `Transpose2DWithUnitDimToShapeCast` - rewrites 2D `vector.transpose`
    as `vector.shape_cast` (there has to be at least one unit dim),
  2. `TransposeOpLowering` - the original pattern without the part
    extracted into `Transpose2DWithUnitDimToShapeCast`.

The rationale behind the split:
  * the output generated by `Transpose2DWithUnitDimToShapeCast` doesn't
    really match the intended output from `TransposeOpLowering` as
    documented in the source file - it doesn't make much sense to keep
    it embedded inside `TransposeOpLowering`,
* `Transpose2DWithUnitDimToShapeCast` _does_ work for scalable vectors,
    `TransposeOpLowering` _does_ not.