Load GNUnet's plugins even when ProjectData is different (patch)

[Alessio Vanni]

Hello,

the attached patch is an extended version of [0], as at the time I
didn't realize that e.g. re:claimID also loads plugins the same way.

As explained both in the linked discussion and in the commit message,
when the ProjectData structure is not GNUnet's default one (i.e. any
third-party application not included in GNUnet's distribution) the
lazy-loading of plugins will search for them in the application's paths
instead of GNUnet's.

This patch only affects the parts using `GNUNET_PLUGIN_load_all', so
those functions using `GNUNET_PLUGIN_load' are still affected by the
bug; however, a quick search shows that the latter function is used in
places that, under normal circumstances, do not interact with the
application's ProjectData (for example, TRANSPORT or ATS startup), so
there shouldn't be any immediate issue.

Thanks,
A.V.

[0] https://lists.gnu.org/archive/html/gnunet-developers/2020-07/msg00049.html

0001-Add-macro-to-load-plugins-within-GNUnet-s-context.patch
Description: patch for gnunet