Change tag type (int -> uint) and add the tag MG_OVERLAP (for ParMmg)

[laetitia-m]

1. The type of tag was signed integer int, and in now unsigned integer uint. This was needed to be able to add extra tags if wanted.
2. In the file common/mmgcommon_private.h: add the tag MG_OVERLAP useful to create and delete the overlap in ParMmg.
3. In the file mmg3d/hash_3d.c, function MMG5_bdrySet: skip some part of the analysis if the tetra is tagged MG_OVERLAP - useful when an overlap is created in ParMmg to ignore overlapping tetra.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 57.89474% with 16 lines in your changes missing coverage. Please review.

Project coverage is 50.44%. Comparing base (2263f92) to head (176f3b2). Report is 17 commits behind head on develop.

Files with missing lines	Patch %	Lines
cmake/testing/code/mmg_get_tagname.c	0.00%	8 Missing :warning:
src/mmg3d/hash_3d.c	50.00%	5 Missing :warning:
src/common/API_functions.c	0.00%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #280 +/- ## =========================================== - Coverage 50.46% 50.44% -0.02% =========================================== Files 176 177 +1 Lines 47224 47236 +12 Branches 10267 10276 +9 =========================================== - Hits 23832 23830 -2 - Misses 15657 15674 +17 + Partials 7735 7732 -3 ```

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