[mlir][vector] Standardize `base` Naming Across Vector Ops (NFC) (#137859)

[mlir][vector] Standardize base Naming Across Vector Ops (NFC)

This change standardizes the naming convention for the argument
representing the value to read from or write to in Vector ops that
interface with Tensors or MemRefs. Specifically, it ensures that all
such ops use the name `base` (i.e., the base address or location to
which offsets are applied).

Updated operations:

* `vector.transfer_read`,
* `vector.transfer_write`.

For reference, these ops already use `base`:

* `vector.load`, `vector.store`, `vector.scatter`, `vector.gather`,
  `vector.expandload`, `vector.compressstore`, `vector.maskedstore`,
  `vector.maskedload`.

This is a non-functional change (NFC) and does not alter the semantics of these
operations. However, it does require users of the XFer ops to switch from
`op.getSource()` to `op.getBase()`.

To ease the transition, this PR temporarily adds a `getSource()` interface
method for compatibility. This is intended for downstream use only and should
not be relied on upstream. The method will be removed prior to the LLVM 21
release.

Implements #131602

0 files changed, 0 insertions, 0 deletions