[mlir][bazel] Move InliningUtils into a separate target. (#85411)
Various (in-tree as well as downstream) targets currently depend on
`InliningUtils.h` to avoid circular dependencies. E.g. `TransformUtils`
depends on `ArithDialect`, so `ArithDialect` can't depend on
`TransformUtils` exporting `InliningUtils.h`. This change exposes that
header and it's implementation as a separate target. Having targets that
implement all the declared functions is the preferred approach for bazel
build graphs.
See also PR #84878, which moves the interface definitions to a separate
file in the `Interfaces` directory. This turned out to be controversial
and putting it in a different directory didn't seem to have any support
either. Instead, this PR only changes the bazel build without moving any
C++ code.