Support names for Updates repositories in product definition

[jcompagner]

2 editors are changed: product file editor and then the repository section but also the category editor which uses the same stuff (code is very simular)

UI part for eclipse-equinox/p2#345

[HannesWell]

Thanks @jcompagner for this PR.
I had only time for a quick look yet, but it looks good so far.

But please revert all the changes in the launch config. Those are not related.

[github-actions]

Test Results

     270 files  +       6       270 suites  +6   1h 13m 56s ⏱️ + 23m 17s
  3 327 tests  -        1    3 297 ✔️ ±       0  30 💤 ±  0  0 ❌  - 1 
10 278 runs  +2 721  10 188 ✔️ +2 698  90 💤 +24  0 ❌  - 1 

Results for commit 373e5aa. ± Comparison against base commit b3d1df7.

This pull request removes 1 test.

AllPDETests org.eclipse.pde.ui.tests.launcher.AllLauncherTests org.eclipse.pde.ui.tests.launcher.FeatureBasedLaunchTest ‑ Unknown test

♻️ This comment has been updated with latest results.

[HannesWell]

Thanks @jcompagner for this PR.

I did a few cosmetic changes, unified the order of some elements, moved the URL and name trimming to the canonical constructor of the RepositoryResult record and adjusted the reference to the P2-issue (since it is in another repo, the full URL is required).

Furthermore I improved the handling of empty names so that in case one leaves the name blank the name element is not written. This is especially important since no existing product has the name element and will therefore first have a null name read when being loaded the next time. Without consideration the name null would be set and we would suddenly have many repos named null. Long story short, if no name element exists none will be added automatically but one actively has to add a name. In order to remove an existing name, one can just clear the name field.

With that this is ready.

product file editor and then the repository section but also the category editor which uses the same stuff (code is very simular)

Indeed I'm tempted to unify this code as far as possible but this is something for follow up PRs.
In general I would also like to make the dialog to enter the name and the URL obsolete and let users just enter the name and URL in the table directly.

[HannesWell]

I also checked the processing of category.xml files in p2 and it looks like that is already handled, so nothing needs to be done for that part:

https://github.com/eclipse-equinox/p2/blob/e55ba98eadc7e7d9d1e8630ad48187a62546b230/bundles/org.eclipse.equinox.p2.updatesite/src/org/eclipse/equinox/internal/p2/updatesite/CategoryParser.java#L695-L703