Add H2 into our fuel media

[pierre-eliep-met]

Goal

This PR shows how to add H2 to our current fuel media.
We can either merge it and it will be a breaking change but require a limited amount of work, simply add one equation, saying that H2 fraction is zero, or we can just close it and leave it as a how to add a different species in our fuel.

I am sure that I made the changes correctly because I made a temporary variable to compute LHV directly, instead of using HHV, and I found the same result when varying H2 proportion :

Units.SpecificEnthalpy LHV = HHV - 2202.92069 *  X_fuel_H*1e4 "J/kg can be assigned in component modifiers";
Units.SpecificEnthalpy LHV_test = (lhv_mass_H2*X_fuel_H2 + lhv_mass_CH4*X_fuel_CH4 + lhv_mass_C2H6*X_fuel_C2H6 + lhv_mass_C3H8*X_fuel_C3H8 + lhv_mass_C4H10*X_fuel_C4H10_n_butane)*1e6;

Type of change

• Bugfix
• New feature
• Refactoring change
• Release & Version Update (don't forget to change the version number in package.mo)

Will it break anything in previous models ?

• Breaking change (If yes, make sure to point it out in the changelog)
• Non-Breaking change

Checklist

• I have added the appropriate tags, reviewers, projects (and detailed the size and priority of my PR) and linked issues to this PR
• I have performed a self-review of my own code
• I have checked that all existing tests pass
• I have checked that my work is compatible with OpenModelica
• I have added/updated tests that prove my development works and does not break anything.
• I have made corresponding changes or additions to the documentation (in Notion documentation)
• I have added corresponding entries to the Changelog
• I have checked for conflicts with target branch, and merged/rebased in consequence

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