Name collisions can become a big issue in liboverrides when production
files gets messy (weird overrides duplicates, bad resync with heavily
changing assets, etc.).
This commit tries to alleviate a bit the problem by generating 'more
unique' names for liboverrides, when an exact match with the reference
is not possible.
So by default, in most common case, the liboverride ID will still have
the exact same name as its linked reference.
If this is not possible, then the new liboverride ID will get a name
which is unique to within the whole current Main (for its ID type). In
particular, this ensure that new override IDs are either named exactly
as their references, or have a name which is not used by any other
reference (linked) IDs.
Note that this is not a perfect solution, since changes in library data
can lead to name collisions later on. However, it should greatly reduce
the frequency of such problems.
Bastien Montagne
e11da03e7a