Merge evaluate_stateless into evaluate,

[panarch]

Add async to evaluate_stateless.
Rename existing evaluate to evaluate_inner which takes storage param as optional.
Make both evaluate and evaluate_stateless use evaluate_inner.
Remove stateless-only Context and merge that into RowContext.
Update JsonStorage and SledStorage to use nested async executor runtime using smol.

[coveralls]

Pull Request Test Coverage Report for Build 4706829324

• 328 of 353 (92.92%) changed or added relevant lines in 26 files are covered.
• 2 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.02%) to 98.816%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
core/src/data/interval/string.rs	5	6	83.33%
core/src/data/row.rs	4	5	80.0%
core/src/executor/aggregate/mod.rs	3	4	75.0%
core/src/executor/insert.rs	37	38	97.37%
core/src/store/data_row.rs	7	8	87.5%
core/src/executor/alter/table.rs	12	14	85.71%
core/src/executor/aggregate/state.rs	30	33	90.91%
core/src/executor/select/mod.rs	44	47	93.62%
storages/sled-storage/src/store_mut.rs	91	94	96.81%
core/src/executor/context/row_context.rs	4	8	50.0%

Files with Coverage Reduction	New Missed Lines	%
core/src/ast/mod.rs	1	99.83%
core/src/executor/validate.rs	1	99.24%

Totals
Change from base Build 4706806160:	-0.02%
Covered Lines:	42216
Relevant Lines:	42722

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💛 - Coveralls