Purpose
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We want to clear the accounting access groups when only the Invoicing application is installed as follows:
If only Invoicing is installed, we should only have 2 groups: `Billing` and `Billing Manager`
If Accouting and Finance is installed, we should have the current groups: `Billing`, `Accountant` and `Advisor`
Specification
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1/ If we have only Invoicing the should have the following hierarchy:
group_account_manager (Billing Manager) ---Implies---> group_account_invoice (Billing)
group_account_user (Accountant) is a technical group out the Accouting groups hierarchy
2/ If we have Accouting and Finance installed, we should then have:
group_account_manager (Advisor) ---Implies---> group_account_user (Accountant) ---Implies---> group_account_invoice (Billing)
The reason we want to keep the group_account_user is that we will hide the accouting fields (account_id,...) with this group, allowing the consultants to show the accouting related information on support.