Implement aggregate functions for sparse vector. (#476)

* Implement aggregate functions for sparse vector.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* fix NULL.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* use iter for div.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* use null for initcond.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* Implement sparse accumulate state.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* add more tests.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* fix replace & clippy.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* Simplify & fix zero panic.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* add random test for aggregate.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* move svec aggregate to single file.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* fix sql.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* fix: rename state.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* fix: rename state.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* rm toast & use internal as stype.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* use internal type & switch memory context.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* fix capacity check.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* use macro to switch context.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* fix merge.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* switch context in c way and rm option of internal.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* fix context.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

* rm useless codes.

Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

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Signed-off-by: my-vegetable-has-exploded <wy1109468038@gmail.com>

Author: my-vegetable-has-exploded