Update the campaign bundle builder to support edits

[hopsoft]

Feature Request

What problem does this solve

The sales team often needs to make changes to campaign bundles after they've been created. Namely adding/removing campaigns.

Describe the solution you'd like

We need the ability to edit a campaign bundle and modify the number of campaigns contained within it. It would also be nice to retain the ability to modify audience targeting, URLs, etc... during bundle editing.