Fix keyset pagination for dependency aggregations

What does this MR do and why?

Fix two issues with keyset pagination on the dependency list.

1. All columns in the cursor need to be returned in the select statement
2. arel_table needs to be used for column_expression to ensure that values are correctly serialized

[7] pry(main)> column_definition = Arel.sql("outer_occurrences.highest_severity")
=> "outer_occurrences.highest_severity"
[8] pry(main)> column_definition.gt('low').to_sql
=> "outer_occurrences.highest_severity > 'low'"
[10] pry(main)> column_definition = Sbom::Occurrence.arel_table.alias('outer_occurrences')[:highest_severity]
[11] pry(main)> column_definition.gt('low').to_sql
=> "\"outer_occurrences\".\"highest_severity\" > 4"

This change is currently behind a feature flag named rewrite_sbom_occurrences_query.

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Before	After

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When testing locally, this still appears to be broken because there is a frontend bug which also needs to be fixed. RSpec tests have been updated to verify correct backend behavior.