Add electrons with brem correction

Add electrons with bremsstrahlung correction to standard_particles:

• new make_long_electrons_with_brem: takes as input make_long_electrons_no_brem and make_photons and uses the new ParticleWithBremMaker introduced in Phys!820 (merged) to create electrons with brem correction applied
• modify make_detached_ee so input electrons can be passed as an option, defaulting to make_long_electrons_no_brem, which was previously hardcoded
• new make_ee_with_brem: takes as input a container of electrons and uses the new FunctionalDiElectronMaker introduced in Phys!820 (merged) to create dielectrons with brem correction applied, ensuring the same photon is not used to correct both electrons in the pair
• new make_detached_ee_with_brem: creates electrons using make_long_electrons_no_brem, filters them with detachment requirements following the selection in make_detached_ee and created dielectrons with brem correction using the above make_ee_with_brem

Add also Hlt2Conf.test_hlt2_bremsstrahlung to test the new standard particles. Three B2JpsiK_ee lines are run using make_detached_ee, make_detached_ee with make_long_electrons_with_brem, and make_detached_ee_with_brem, respectively. Currently only check for no errors and at least 1 selected candidate.

Needs Phys!820 (merged) and lhcb-datapkg/PRConfig!175 (merged)

Closes #214 (closed)