[Encoding] Implement OpAsmDialectInterface for IREE Encoding dialect. (#19146)

The revision implements the dialect interface which hoists the encodings
out of the tensor type. It makes IR dumps much easier in terms of
readability because the same encodings are collapsed into a single one
and the alias is shorter.

The revision refines the lit checks for
Encoding/IR/test/roundtrip.mlir which makes the style consistent; it
adapts some tests to hoist the encodings, which matches the IR dumps.

The `IREEEncodingInlinerInterface` is renamed to
`EncodingInlinerInterface` in this patch for consistency. The `IREE`
prefix is redundant because it is already in an anonymous namespace
under the IREE namespace.

Fixes https://github.com/iree-org/iree/issues/19024

Signed-off-by: hanhanW <hanhan0912@gmail.com>