Eclipse Launch Configuration: group by project and add convenient filters

Let's make sure issue is not already fixed in latest builds first.

- [x] I verified [latest Integration Build of Eclipse SDK](https://download.eclipse.org/eclipse/downloads/) doesn't provide the feature.

## Suggestion

I have many launch configurations belonging to different projects, and it would be user-friendly to be able to group the launch configurations by the workspace location of the project ${workspace_loc} (i.e., project folder).

Currently, grouping is only possible by launch type:

For example, I also used `Eclipse Runner` plugin (see https://github.com/zaunerc/eclipserunnerplugin), which allowed me to group tasks by own folders:

**Ideally, all launch configurations would be grouped by project and, within the project, by launch type.**

The `Eclipse Runner` plugin also has 3 predefined filters which makes the maintainability of launch configurations easier:

- Filter closed projects
- Filter deleted projects (to easily remove orphaned tasks manually)
- Filter current project (shows only the launch configuration of the currently focused project)

**Would be nice to also add those filters to the `Eclipse Launch Configuration`-View.**

To sum up:
1. Please add "Group by workspace" (as described above)
2. Please add "Filters" (as described above)

## Community

- [x] I understand suggesting an enhancement doesn't mandate anyone to implement it. Other contributors may consider this suggestion, or not, at their own convenience. The most efficient way to get it fixed is that I implement it myself and contribute it back as a good quality patch to the project.

Beginnen Sie mit der in der Issue beschriebenen Ansicht „Eclipse Launch Configuration“ und vergleichen Sie deren aktuellen Gruppierungsoptionen mit dem Eclipse Runner plugin. Legen Sie fest, wie „Group by workspace“ Projekte und Launch-Typen verschachteln soll, und überprüfen Sie anschließend die drei angeforderten Filter: geschlossene Projekte, gelöschte Projekte und das aktuelle Projekt.

Vom Indexierungsmodell aus dem Issue-Text verfasst.