Change tool filter to not extend simple filter

What does this MR do and why?

This MR changes tool_filter.vue to no longer extend simple_filter.vue by copying the same code that the other filters use (severity_filter.vue, status_filter.vue, etc). This allows us to remove simple_filter.vue in a follow-up MR. There are no UI or behavior changes otherwise.

How to set up and validate locally

1. Enable the refactor_vulnerability_tool_filter feature flag.
2. Create a new group.
3. Clone this project into the group: https://gitlab.com/svedova/test-remediations-v2
4. Run a pipeline against the master branch for the project.
5. Go to the group vulnerability report.
6. Verify that the tool filter dropdown is shown and is working as intended.
7. Click on the hamburger menu on the upper left and click on Security.
8. Go to Security -> Settings, search for the project you just cloned, and add it.
9. Go to Security -> Vulnerability report.
10. Verify that the tool filter dropdown is shown and is working as intended.

2023-04-11_01-10-07

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #393102 (closed)