[mlir] Support DialectRegistry extension comparison (#101119)

`PassManager::run` loads the dependent dialects for each pass into the
current context prior to invoking the individual passes. If the

[mlir] Support DialectRegistry extension comparison (#101119)

`PassManager::run` loads the dependent dialects for each pass into the
current context prior to invoking the individual passes. If the
dependent dialect is already loaded into the context, this should be a
no-op. However, if there are extensions registered in the
`DialectRegistry`, the dependent dialects are unconditionally registered
into the context.

This poses a problem for dynamic pass pipelines, however, because they
will likely be executing while the context is in an immutable state
(because of the parent pass pipeline being run).

To solve this, we'll update the extension registration API on
`DialectRegistry` to require a type ID for each extension that is
registered. Then, instead of unconditionally registered dialects into a
context if extensions are present, we'll check against the extension
type IDs already present in the context's internal `DialectRegistry`.
The context will only be marked as dirty if there are net-new extension
types present in the `DialectRegistry` populated by
`PassManager::getDependentDialects`.

Note: this PR removes the `addExtension` overload that utilizes
`std::function` as the parameter. This is because `std::function` is
copyable and potentially allocates memory for the contained function so
we can't use the function pointer as the unique type ID for the
extension.

Downstream changes required:
- Existing `DialectExtension` subclasses will need a type ID to be
registered for each subclass. More details on how to register a type ID
can be found here:
https://github.com/llvm/llvm-project/blob/8b68e06731e0033ed3f8d6fe6292ae671611cfa1/mlir/include/mlir/Support/TypeID.h#L30
- Existing uses of the `std::function` overload of `addExtension` will
need to be refactored into dedicated `DialectExtension` classes with
associated type IDs. The attached `std::function` can either be inlined
into or called directly from `DialectExtension::apply`.

---------

Co-authored-by: Mehdi Amini <joker.eph@gmail.com>

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[mlir] move PDL-related transform ops into an extension

The initial bring-up of the Transform dialect relied on PDL to provide
the default handle type (`!pdl.operation`) and the matching capability.

[mlir] move PDL-related transform ops into an extension

The initial bring-up of the Transform dialect relied on PDL to provide
the default handle type (`!pdl.operation`) and the matching capability.
Both are now provided natively by the Transform dialect removing the
reason to have a hard dependency on the PDL dialect and its interpreter.
Move PDL-related transform operations into a separate extension.

This requires us to introduce a dialect state extension mechanism into
the Transform dialect so it no longer needs to know about PDL constraint
functions that may be injected by extensions similarly to operations and
types. This mechanism will be reused to connect pattern application
drivers and the Transform dialect.

This completes the restructuring of the Transform dialect to remove
overrilance on PDL.

Note to downstreams: flow that are using `!pdl.operation` with Transform
dialect operations will now require `transform::PDLExtension` to be
applied to the transform dialect in order to provide the transform
handle type interface for `!pdl.operation`.

Reviewed By: springerm

Differential Revision: https://reviews.llvm.org/D151104

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