Reject trailing data in SGL WKB inputs

[matthiasgoergens]

Spatial's SGL reader returned success as soon as it finished the outermost WKB
geometry, even when bytes remained in the input. The 2D constructors,
ST_GeomFromHEXWKB, and statistics parsing could consequently accept a valid
geometry followed by arbitrary data or a second geometry.

Require the parser position to reach the end of the supplied buffer in both
the materialising and statistics paths, and report a specific trailing-data
error otherwise. The standalone regression also verifies the error category,
message, and successful reader reuse after a rejected input.

The standalone Clang ASan/UBSan suite and the full Spatial relassert build
pass. Focused SQL coverage exercises all three 2D constructors and HEX WKB;
the adjacent WKB round-trip suites also pass.

Related: duckdb/duckdb#24296 and duckdb/duckdb#24301 — the corresponding
DuckDB core ST_GeomFromWKB path is fixed separately in duckdb/duckdb#24559.

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Verified (2026-08-05): test/sql/geometry/st_2d_fromwkb.test and
test/sql/geometry/st_ashexwkb.test fail on unpatched duckdb-spatial main
2b072abd2a (trailing bytes silently accepted, e.g. a point followed by
garbage still returns POINT_2D {'x': 1.0, 'y': 2.0}) and pass with this
branch (6 and 27 assertions).

[matthiasgoergens]

Same CI failure as #855 — pre-existing build break against duckdb core main (PR #24278 changed table_function_bind_t signature), not caused by this PR. Details in the #855 comment.

[matthiasgoergens]

Retargeted to v1.5-variegata together with #855, see the note there. No overlap with #867, which handles empty or truncated input in the serialization reader; this one rejects trailing bytes after a complete WKB geometry in the SGL reader.