Use shorter aliases in CSE (apache#10939)

* initial change

* test renaming

* use counter instead of indexmap

* order slt tests

* change cse tests

* restore slt tests

* fix slt test

* formatting

* ensure no alias collision

* keep original alias numbers for collision

* ensure no collision in aggregate cse

* use `AliasGenerator` to generate aliases, use `__cse` prefix in common expression aliases, remove `DataType` from `ExprStats` as not needed, store aliases in `CommonExprs`, revert unnecessary changes

* use `into_values()` instead of `into_iter()` where possible

* fix docstring of `ExprStats` and `CommonExprs`

* use `__common_expr` prefix

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Co-authored-by: Mohamed Abdeen <[email protected]>