The separate Kenyan payroll benefits module has been folded back into the main Kenyan payroll module, simplifying setup and maintenance. Unused fields were removed, and payslip styling was made more flexible so payroll reports can better reflect configured salary lines.

Before this commit, a module named l10n_ke_hr_payroll_bik
was created in order to implement some new fields in stable.
This commit moves that module back into l10n_ke_hr_payroll and
removes unused fields.
    
task-3029348