RasterRef and BandRef accessors over the canonical N-D schema:
spatial_dims/spatial_shape, transform, crs, num_bands, band(i), and
band-level dim_names, source_shape, shape (visible, derived from view),
view, data_type, nodata, outdb_uri, outdb_format, nd_buffer,
contiguous_data returning Cow<[u8]>.

validate_view enforces all view rules including i64-overflow on
start + (steps-1)*step. NdBuffer exposes raw buffer + shape + byte
strides + offset for zero-copy access (numpy / Arrow C Data Interface
boundary); VIEW → byte strides happens inside nd_buffer().

Adds BandRef::is_2d() default method as the gate GDAL-backed paths
use to refuse N-D input cleanly: true iff dim_names == ["y","x"]
over the identity view.

… reader/builder + RS_* migration

View-aware Arrow reader (RasterStructArray, BandRefImpl) with corruption-
surgery (negative steps, bad source_axis, length mismatch) that
round-trips an ArrowError. Builder exposes start_raster / start_band
for full N-D plus start_raster_2d / start_band_2d for legacy 2D, with
identity-view default written as a null view row. finish_raster
validates each band's visible shape against the raster's spatial_shape
along the spatial dims.

All 33 RS_* functions migrated mechanically; outputs on 2D inputs are
byte-identical to apache#787. RS_BandPath keeps its existing inline
fragment-stripping (format-agnostic display, untouched by the GDAL
parser). Test helpers in sedona-testing rewritten on the N-D builder
API.

Reads outdb_uri + parse_outdb_source instead of apache#787's storage_type /
outdb_url / outdb_band_id triplet. Each GDAL-backed SQL function gates
on BandRef::is_2d() at entry and returns an Execution error on N-D
input. VSI normalization, the dataset cache, and RasterIO bodies are
byte-for-byte unchanged from apache#787 - only the schema-read sites move.

In-db reads use BandRef::contiguous_data() and require Cow::Borrowed
so MEM datasets can point at the StructArray's backing buffer without
copying; for is_2d identity views this always holds.

Tests rebuilt to use RasterBuilder directly. Adds an N-D rejection
test for raster_ref_to_gdal_mem and the VRT path, plus an end-to-end

`raster_ref_to_gdal_mem` previously returned a `Result<Dataset>` and
guarded against `BandRef::contiguous_data()` returning `Cow::Owned`
with a runtime tripwire ("Internal: contiguous_data must be borrowed
for is_2d bands; got owned"). The check was correct — handing GDAL a
pointer into a `Vec<u8>` that drops at the end of the iteration would
dangle — but it ties an internal invariant ("`is_2d` ⇒ Borrowed") to
incidental properties of today's reader. Any future copy path in the
reader (compression, BinaryView block-boundary stitching, alignment
fix-up, sliced/broadcast/transposed views from apache#813 / apache#750) would
detonate the tripwire on perfectly valid 2-D rasters.

Change: return `Result<(Dataset, Vec<Vec<u8>>)>`. On `Cow::Borrowed`
the GDAL band still points directly at the StructArray buffer
(zero-copy). On `Cow::Owned` we move the `Vec<u8>` out of the Cow
without copying — the reader's existing materialization is the only
allocation — and stash it in the returned vector. The caller (the
provider in `gdal_dataset_provider.rs`) parks it in a new
`RasterDataset::_owned_band_bytes` field that lives as long as the
MEM dataset that holds the pointers.

`raster_ref_to_gdal_empty` discards the always-empty vector.

Re-enables non-null `view` rows in the N-D raster reader. PR-B treats a
non-null view as a hard read error because its only writer (start_band)
emits the canonical identity (null view row); the view → byte-stride
composition path is needed by the slice/manipulation functions
(RS_Slice, RS_SliceRange, RS_DimToBand, RS_BandToDim) that land on
top of this PR.

Reintroduced:

- traits.rs: validate_view() + 22 unit tests.
- builder.rs: start_band_with_view() builder API and ~12
  view-construction tests (slice, broadcast, transpose, negative-step,
  IPC round-trip, etc.).
- array.rs: view → byte-stride composition in nd_buffer(), view-aware
  contiguous_data() Cow::Owned strided-copy slow path, and the array
  reader tests for explicit views (negative steps, OOB axis, length
  mismatch, malformed view rejection).

Identity-view writer/reader behavior is unchanged; PR-B's error path on
non-null view rows is replaced by the composition path validated here.