Split sample_bipartite() into two functions for the G(n,m) and G(n,p) case

[szhorvat]

What is the feature or improvement you would like to see?

Separate sample_bipartite() into sample_biparite_gnm() and sample_bipartite_gnp(), and eventually deprecate sample_bipartite().

Motivation

• Consistency with the separate sample_gnm() and sample_gnp()
• The $G(n,p)$ and $G(n,m)$ models are conceptually distinct
• Reduces the number of optional argument
• Explicit function names that reduce confusion
• Already have separate igraph_bipartite_game_gnp() and igraph_bipartite_game_gnm() available in C/igraph

References

• https://igraph.org/r/doc/sample_bipartite.html

[szhorvat]

Consider this for 2.0 @krlmlr @maelle?

[maelle]

Noting that if we do, the deprecation code for bipartite.random.game() will need to be updated.