Add has_remediations column to vulnerability_reads table

What does this MR do and why?

This is a migration to add column to vulnerability_reads table.

Related to #420617 (closed)

Database review

rake db:migrate:up

main: == [advisory_lock_connection] object_id: 224640, pg_backend_pid: 65940
main: == 20230810132301 AddHasRemediationsToVulnerabilityReads: migrating ===========
main: -- add_column(:vulnerability_reads, :has_remediations, :boolean, {:default=>false})
main:    -> 0.0227s
main: == 20230810132301 AddHasRemediationsToVulnerabilityReads: migrated (0.0295s) ==

main: == [advisory_lock_connection] object_id: 224640, pg_backend_pid: 65940

rake db:migrate:down

main: == [advisory_lock_connection] object_id: 224740, pg_backend_pid: 65492
main: == 20230810132301 AddHasRemediationsToVulnerabilityReads: reverting ===========
main: -- remove_column(:vulnerability_reads, :has_remediations, {:if_exists=>true})
main:    -> 0.1157s
main: == 20230810132301 AddHasRemediationsToVulnerabilityReads: reverted (0.1189s) ==

main: == [advisory_lock_connection] object_id: 224740, pg_backend_pid: 65492

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.