Refactor HighsCliqueTable::addClique

[fwesselm]

• Refactor HighsCliqueTable::addClique and related code
• HighsCliqueTable::addClique now checks if an equality clique with two elements is passed and automatically considers the complemented clique as well (i.e. x_1 + x_2 <= 1 and (1 - x_1) + (1 - x_2) <= 1, which is useful for equality cliques identified by solution enumeration).
• Computational results are very similar to the baseline, so average performance is not affected very much. However, the new code is very helpful on individual models.

[fwesselm]

code-coverage is falling with the following error:

lcov: ERROR: 'exclude' pattern 'app/CLI11*' is unused.
	(use "lcov --ignore-errors unused ..." to bypass this error)