[mlir][core] Fix inline pass default pipeline dump

[mlir][core] Fix inline pass default pipeline dump

The inliner pass performs canonicalization when created programtically, run with `mlir-opt` with default options, or when explicitly specified. However, when running the pipeline resulting from a `-dump-pass-pipeline` on a default inline pass, the canonicalization is not performed as part of the inlining. This is because the default value for the `default-pipeline` option of the inline pass is an empty string, and this is selected during the dumping. When `InlinerPass::initializeOptions` detects the empty string, it sets the `defaultPipeline` to `nullptr`, which was previously set to canonicalize in the `InlinerPass` constructor, thus the canonicalization is not performed.

The added test checks if the inline pass performs canonicalization by default, and that the dumped `default-pipeline` is set to `canonicalize`.

Fixes: https://github.com/llvm/llvm-project/issues/60960

Reviewed By: rriddle

Differential Revision: https://reviews.llvm.org/D145066