Expose new lrslib features: lrsnash, 2nash

[mkoeppe]

#20886 upgraded lrslib to version 6.2. This version, according to http://cgm.cs.mcgill.ca/~avis/C/lrs.html, has the following new features:

• lrsnash, 2nash: Computes all Nash equlibria of a two person non-cooperative game. 2nash is a 2-processor parallel version

Depends on #20886
Depends on #21012

CC: @dimpase @videlec @mkoeppe @fchapoton @kiwifb @tscrim @drvinceknight @theref @jdemeyer @kcrisman

Component: game theory

Issue created by migration from https://trac.sagemath.org/ticket/20969

[dimpase]

comment:1

note that there is some lrslib/Nash things already in Sage, see
sage/game_theory/normal_form_game.py: sage: g.obtain_nash(algorithm='lrs') # optional - lrslib

[mkoeppe]

comment:2

#21012 already uses lrsnash as replacement for old nash.

[mkoeppe]

Changed dependencies from #20886 to #20886, #21012