Add optional parameter to `make_ace` for equi-probable angles needed

[janmalec]

Description

Added an optional parameter to openmc.data.njoy.make_ace to specify the number of equi-probable angles. The default value in OpenMC is low, which helps reduce file size but can significantly impact benchmarking accuracy. This change makes OpenMC more immediately useful for benchmarking new libraries while maintaining flexibility for users.

See the IAEA report for more details on processing options.

Compatibility

The parameter is optional and defaults to 12, so there should be no breaking changes.