Perf: Introduce zero copy path when tonic returns an aligned buffer (#10273)

# Which issue does this PR close?

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- works towards #10125

# Rationale for this change
see
#10206 (comment)

If the buffer Tonic returns happens to be 64-bit aligned ([as the Arrow
spec
requires](https://arrow.apache.org/docs/format/Columnar.html#buffer-alignment-and-padding)),
we can wrap it directly via `Buffer::from(Bytes)`, a zero-copy path that
just increments a reference count. If not, `Buffer::from(&[u8])` copies
into a fresh aligned allocation. The check is cheap (a single pointer
modulo), and can save a potentially very large buffer copy.
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# What changes are included in this PR?

this PR adds a pointer check for the data body. if the buffer is aligned
to a 64 bit address no copy happens, otherwise copy the bytes as usual.
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# Are these changes tested?
existing test cover this. if the buffer isn't aligned we fallback to
copying it.
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# Are there any user-facing changes?
no
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Author: Rich-T-kid

arrow-flight/src/decode.rs

@@ -336,8 +336,17 @@ impl FlightDataDecoder {
                         "Unable to convert flight data header to a record batch".to_string(),
                     )
                 })?;
+                let buffer = {
+                    // see https://arrow.apache.org/docs/format/Columnar.html#buffer-alignment-and-padding
+                    // reuse the allocation if already aligned, otherwise copy into a fresh aligned buffer.
+                    if data.data_body.as_ptr() as usize % 64 == 0 {
+                        &Buffer::from(data.data_body.clone())
+                    } else {
+                        &Buffer::from(data.data_body.as_ref())
+                    }
+                };
                 let batch = arrow_ipc::reader::RecordBatchDecoder::try_new(
-                    &Buffer::from(data.data_body.as_ref()),
+                    buffer,
                     record_batch,
                     Arc::clone(&state.schema),
                     &state.dictionaries_by_field,