Remove const generic from coord buffers #2100

Job	Run time
build-benchmarks	2m 37s
check-features	15s
check-features-with-external-dependencies (-F gdal -F gdal/bindgen)	42s
check-features (-F csv)	35s
check-features-with-external-dependencies (-F geos)	19s
check-features (-F flatgeobuf)	15s
check-features-with-external-dependencies (-F proj)	44s
Lint and Test	8m 11s
check-features (-F flatgeobuf_async)	33s
check-features (-F ipc_compression)	24s
check-features (-F parquet)	16s
check-features (-F parquet_async)	33s
check-features (-F parquet_compression)	22s
check-features (-F polylabel)	12s
check-features (-F postgis)	30s
check-features (-F rayon)	28s
	16m 56s

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