[MeshGmshLoader] Handle recent MSH format (sofa-framework#2155)

* [GmshLoader] Add test

At the moment the test fails, because there seem to be some discrepancy
between the topology that the MeshGmshLoader is able to retrieve in a
scene, and the data it actually contains. This might come from the fact
that the doLoad() method of MeshGmshLoader doesn't call anymore
its method readGmsh, and that the mesh is in fact retrieved in the scene
at the MeshGmsh level. This has yet to be clarified.

* [GmshLoader] Update .msh file parsing to handle version 4

Parsing method readGmsh is updated to handle more recent MSH file
formats (<= 4.1). Detail of the format is available here:
https://gmsh.info/doc/texinfo/gmsh.html#File-formats

Handling of versions <= 2 is not changed, so this commit should not be
breaking.

* [GmshLoader] Update MSH format version detection

Instead of assuming that the MSH file format version is either 1 or 2,
we read it from the file in order to handle the most recent format (4.1
at the time). The version is then passed to the parser in MeshGmsh.cpp.
With this commit, versions >= 4 are not yet handled by the parser.

* [GmshLoader] Correct loop indentation

* [GmshLoader] Propagate MeshGmsh new code to MeshGmshLoader

Method readGmsh of MeshGmshLoader is left unused.

* [GmshLoader] Add safety check on while loop

In case the MSH file format is only partially respected by the input
file.

* [GmshLoader] Fix regression

The use of std::getLine instead of the >> operator caused the parsing to
read the last " " character of the last line in the "Element" section in
the MSH files, instead of the line closing the section, for file formats
older than 2.0.

* [GmshLoader] Fix test

Using the data obtained via the official Gmsh loader as a reference.

* Fix unnoticed differences after master update

* Fix detection of .msh files with version 1.x

The first line of old .msh files (version = 1.x) seems to be "$NOD\r"
instead of "$NOD", which caused them not to be detected by the
MeshGmshLoader parser. This issue comes from the fact that before the
update of the loader, if the header line was not recognised, then the
version of the parsed .msh file was assumed to be 2.x.

This fix simply adds $NOD\r$ as a recognised header line for .msh files
with version 1.x, mainly to maintain compatibility with the unit tests.

* Add node in MeshGmshLoader.scn to test msh v >= 4.0

Basic modification of examples/Components/loader/MeshGmshLoader.scn
adding a new node which parses a .msh file with version 4.1

* Fix failing tests

Some tests in the CI use .msh files with slightly different syntax than
the standard. Namely, the problem comes from the presence of a carriage
return character "\r", sometimes preceeded by a space " " character, at
the end of main section lines such as "$MeshFormat \r", or "$Nodes\r".
A solution to this is to make the parser a little bit more permessive,
by only parsing the beginning of these lines and see if it corresponds
to the expected section titles ("$MeshFormat", "$Nodes"). This is only
implemented for versions <= 2, as it is not actually part of the
standard (i.e. a .msh file starting with "$MeshFormat \r" instead of
"$MeshFormat" is not technically a .msh file).
The issue could come from .msh files commited from different OS, with
lines ending differently. If so, the more permessive parsing should also
be extended for versions >= 4.

* Fix typo, fixing failing tests

">" instead of ">=" caused (logically) some header lines not to be
detected as .msh header lines

Co-authored-by: Camille Krewcun <camille.krewcun@inria.fr>
Co-authored-by: Camille <camille.krewcun@uca.fr>