Add particle species in Beam classes and update tracking methods

[cr-xu]

Description

Add the option to track with different particle species.

Changes:

• Introduce a new Species Class, containing the name, charge, and mass information for the particles. Some basic species are pre-defined, with the possibility to define custom mass-to-charge ratio particles.
• Now the transfer_map methods and the compute_relativistic_factors need two arguments:[energy, particle_mass_eV] with particle_mass_eV default to electron mass
• Beam classes now have a new attribute species and a new property mass_eV
• Added new benchmark tests by running bmad simulations directly
• Updated the CI/CD pipelines to install bmad with conda; separated Windows tests to run only the tests without bmad.

Motivation and Context

• I have raised an issue to propose this change (required for new features and bug fixes)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (update in the documentation)

Checklist

• I have updated the changelog accordingly (required).
• My change requires a change to the documentation.
• I have updated the tests accordingly (required for a bug fix or a new feature).
• I have updated the documentation accordingly.
• I have reformatted the code and checked that formatting passes (required).
• I have have fixed all issues found by flake8 (required).
• I have ensured that all pytest tests pass (required).
• I have run pytest on a machine with a CUDA GPU and made sure all tests pass (required).
• I have checked that the documentation builds (required).

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[cr-xu]

I just realized that I still need to take the particle charges into account for the cavities/elements with electric fields. So this should probably wait until #278 is merged.