remove deprecated StructStrategy (#7242)

## Summary

The `StructStrategy` has been deprecated since 0.59.0, and
`TableStrategy` has been the default writer strategy for tabular things
since then as well.

## API Changes

For anyone still using StructStrategy, you can migrate to TableStrategy
by changing


```rust
let writer = StructStrategy::new(child_strategy, validity_strategy);
```

To

```rust
let writer = TableStrategy::new(Arc::new(validity_strategy), Arc::new(child_strategy));
```

**Note that TableStrategy and StructStrategy constructors have their
arguments flipped**

## Testing

We're eliminating code, nothing added.

Signed-off-by: Andrew Duffy <andrew@a10y.dev>

Author: a10y

vortex-layout/public-api.lock

@@ -642,24 +642,6 @@ pub fn vortex_layout::layouts::row_idx::row_idx() -> vortex_array::expr::express
 
 pub mod vortex_layout::layouts::struct_
 
-pub mod vortex_layout::layouts::struct_::writer
-
-pub struct vortex_layout::layouts::struct_::writer::StructStrategy
-
-impl vortex_layout::layouts::struct_::writer::StructStrategy
-
-pub fn vortex_layout::layouts::struct_::writer::StructStrategy::new<S: vortex_layout::LayoutStrategy, V: vortex_layout::LayoutStrategy>(child: S, validity: V) -> Self
-
-impl core::clone::Clone for vortex_layout::layouts::struct_::writer::StructStrategy
-
-pub fn vortex_layout::layouts::struct_::writer::StructStrategy::clone(&self) -> vortex_layout::layouts::struct_::writer::StructStrategy
-
-impl vortex_layout::LayoutStrategy for vortex_layout::layouts::struct_::writer::StructStrategy
-
-pub fn vortex_layout::layouts::struct_::writer::StructStrategy::buffered_bytes(&self) -> u64
-
-pub fn vortex_layout::layouts::struct_::writer::StructStrategy::write_stream<'life0, 'async_trait>(&'life0 self, ctx: vortex_array::ArrayContext, segment_sink: vortex_layout::segments::SegmentSinkRef, stream: vortex_layout::sequence::SendableSequentialStream, eof: vortex_layout::sequence::SequencePointer, handle: vortex_io::runtime::handle::Handle) -> core::pin::Pin<alloc::boxed::Box<(dyn core::future::future::Future<Output = vortex_error::VortexResult<vortex_layout::LayoutRef>> + core::marker::Send + 'async_trait)>> where Self: 'async_trait, 'life0: 'async_trait
-
 pub struct vortex_layout::layouts::struct_::Struct
 
 impl core::fmt::Debug for vortex_layout::layouts::struct_::Struct
@@ -1938,12 +1920,6 @@ pub fn vortex_layout::layouts::repartition::RepartitionStrategy::buffered_bytes(
 
 pub fn vortex_layout::layouts::repartition::RepartitionStrategy::write_stream<'life0, 'async_trait>(&'life0 self, ctx: vortex_array::ArrayContext, segment_sink: vortex_layout::segments::SegmentSinkRef, stream: vortex_layout::sequence::SendableSequentialStream, eof: vortex_layout::sequence::SequencePointer, handle: vortex_io::runtime::handle::Handle) -> core::pin::Pin<alloc::boxed::Box<(dyn core::future::future::Future<Output = vortex_error::VortexResult<vortex_layout::LayoutRef>> + core::marker::Send + 'async_trait)>> where Self: 'async_trait, 'life0: 'async_trait
 
-impl vortex_layout::LayoutStrategy for vortex_layout::layouts::struct_::writer::StructStrategy
-
-pub fn vortex_layout::layouts::struct_::writer::StructStrategy::buffered_bytes(&self) -> u64
-
-pub fn vortex_layout::layouts::struct_::writer::StructStrategy::write_stream<'life0, 'async_trait>(&'life0 self, ctx: vortex_array::ArrayContext, segment_sink: vortex_layout::segments::SegmentSinkRef, stream: vortex_layout::sequence::SendableSequentialStream, eof: vortex_layout::sequence::SequencePointer, handle: vortex_io::runtime::handle::Handle) -> core::pin::Pin<alloc::boxed::Box<(dyn core::future::future::Future<Output = vortex_error::VortexResult<vortex_layout::LayoutRef>> + core::marker::Send + 'async_trait)>> where Self: 'async_trait, 'life0: 'async_trait
-
 impl vortex_layout::LayoutStrategy for vortex_layout::layouts::table::TableStrategy
 
 pub fn vortex_layout::layouts::table::TableStrategy::buffered_bytes(&self) -> u64

vortex-layout/src/layouts/struct_/mod.rs

@@ -2,7 +2,6 @@
 // SPDX-FileCopyrightText: Copyright the Vortex contributors
 
 mod reader;
-pub mod writer;
 
 use std::sync::Arc;
 

vortex-layout/src/layouts/struct_/writer.rs

@@ -1,8 +1,9 @@
 // SPDX-License-Identifier: Apache-2.0
 // SPDX-FileCopyrightText: Copyright the Vortex contributors
 
-//! A more configurable variant of the `StructStrategy` that allows overwriting
-//! specific leaf fields with custom write strategies.
+//! A configurable writer strategy for tabular data.
+//!
+//! Allows the caller to override specific leaf fields with custom layout strategies.
 
 use std::sync::Arc;