Simplify and generalize project imports in P2's Oomph setup

[HannesWell]

The root .project file of p2 is removed via eclipse-equinox/p2#149

The abandoned project 'org.eclipse.equinox.p2.testserver' has been deleted as part of eclipse-equinox/p2#49.

@merks or do you know another reason why multiple source-locators are required?

[github-actions]

Unit Test Results

     24 files       24 suites   11m 23s ⏱️
2 137 tests 2 093 ✔️ 44 💤 0 ❌
2 181 runs  2 137 ✔️ 44 💤 0 ❌

Results for commit c2c6427.

[merks]

It looks like the products folder was deliberately excluded, but I don't see a good reason to exclude it.

Note that in other Git repos that have a .project in the root, I've added filters to eliminate the duplicates (from folders that contain nested projects) while making the root files available as a project.

eclipse-birt/birt#699

https://github.com/eclipse/birt/blob/6dd4b76d1134ca9dfd67eaeda66a076a4b75b9eb/.project#L17-L27

[HannesWell]

It looks like the products folder was deliberately excluded, but I don't see a good reason to exclude it.

The products folder was just added recently via #114 and the setup existed before that, so there is probably no reason. :)

Note that in other Git repos that have a .project in the root, I've added filters to eliminate the duplicates (from folders that contain nested projects) while making the root files available as a project.

eclipse/birt#699

https://github.com/eclipse/birt/blob/6dd4b76d1134ca9dfd67eaeda66a076a4b75b9eb/.project#L17-L27

Thanks for that hint. At least for the other Eclipse Platform repos I found a .project file in the repo root (I checked a few but not all) and therefore went the simple way. But if the .project file in the root is needed, for a reason I don't see at the moment, we can use that filter. 👍🏽