Some bugfixes

• Fix bug in creating zero constants in the editor
• Don't make plans by default to avoid running into issues with repair_plan (all this code is going to get ripped out anyway so this is fine)
• Fix for intra-SROA
• Some more GVN & DCE in default pass order to make cava less inscrutable

requested review from @aaronjc4

assigned to @rarbore2

merged

mentioned in commit 2f6d9505