Bug 21268: Don't remove 0 allocated funds from fund list

Bug 21268: Don't remove 0 allocated funds from fund list

If a fund is created with a amount of 0, it will not appear in the fund
list (when a new order is created for instance).
0 allocated funds can be used to track donations and other situations
where there is not an expected amount for the year.

Test plan:
0. Do not apply the patch
1. Create 1 active and 1 inactive budgets
2. Create some funds for each budgets, with amount > 0 and amount == 0
3. Add orders to basket
=> Note that the funds with amount == 0 are not displayed
4. Apply the patch
5. Add orders to basket (using the different possible ways we have)
=> Note that the funds with amount == 0 are displayed

This change is applied to the different views of the acquisition module.

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
Signed-off-by: Joonas Kylmälä <joonas.kylmala@helsinki.fi>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>