Display project scope values in filter panels

Description
Currently, the filter panel is not tied to a specific scope.
Because custom fields can be configured to show elements depending on the scope (project or global), it is not possible to display exactly the desired elements without knowing the scope. 

User friction
Users are not able to use project scope custom fields in filter panels

Steps to reproduce (right now) / Actual Result:
1. Create a custom field set to a certain Project Scope
2. Open Test Execution issue
3. Go to the Tests section, open Filters
4. Add custom field

IMPACT

What would improve if solved:
The filter panel will be easier to use when custom fields have project-specific values.

Impact on stakeholders:
Users will be able to use a better and more reliable filter

Current workaround:
Use the Advanced Filter for project-specific custom fields

CONTEXT & EXAMPLES:

Concrete example:
When adding a custom field to the Basic filter, users are unable to see the project-specific custom field values. It will either show the global values or "No elements found".

Workaround risk:

Users would need to rely on the Advanced Filter when filtering by custom fields. This can take more time, require more manual input, and may not be as user-friendly for all users.