Expose non-const reference to edges in Graph.hh

[ms-jagadeeshan]

🦟 Bug fix

Fixes #99

Summary

Issue: The Graph::VertexFromId function has two versions that return a const and non-const reference to a Vertex. However there is only a const version of the Graph::EdgeFromId function, which makes it hard to modify Edge Data()

Solution : Have added non-const(mutable) reference function for Graph::EdgeFromId .

Issue: Likewise, the Graph::AdjacentsTo and Graph::AdjacentsFrom functions return non-const references to the graph vertices, while the Graph::IncidentsTo and Graph::IncidentsFrom functions only return const references to the graph edges.

Solution: Removed the const from return type of Graph::IncidentsTo and Graph::IncidentsFrom functions.

[caguero]

I think these changes break ABI (and API). We should retarget the patch to main.

Alternatively, we could add the functions that are missing without changing the existing ones.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.11%. Comparing base (9f55592) to head (11caaf7).

Additional details and impacted files

@@            Coverage Diff            @@
##           gz-math7     #580   +/-   ##
=========================================
  Coverage     94.11%   94.11%           
=========================================
  Files           146      146           
  Lines          9804     9809    +5     
=========================================
+ Hits           9227     9232    +5     
  Misses          577      577           

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[ms-jagadeeshan]

@caguero Thank you for the guiding.
I have reverted back the breaking change, now the change only contain the new function.
Also the second point mentioned in the original issue is not clear, see this #99 (comment)

[caguero]

The new function looks good to me.