Replace default alerts with Toast

[HenrikeW]

Related issue(s) and PR(s)

There were some places left where we used alert. All of them are now replaced with our own Toast, type "warning".

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Other

List of changes made

• because the list of toasts is handled in Report.tsx, a handler function was created and passed on to the child component that needed it (QuickAdd.tsx)
• alerts in QuickAdd and Report were replaced with toasts.

Screenshot of the fix

Just one example.

Testing

Most of the cases are error handling for API requests failing etc, so hard to test.
The one that can be tested is the one on the screenshot above:
Try to add an issue/activity pair that already is part of your list of recent issues.
You should see the toast (was alert before).

Definition of Done checklist

• I have made an effort making the commit history understandable
• I have performed a self-review of my own code and commented any hard-to-understand areas
• Tests and lint/format validations are passing
• My changes generate no new warnings