[16.0] [ADD] pos_receipt_replace_user_by_trigram

[trisdoan]

replace cashier's name by his trigram (first letter of firstname + first 2 letters of lastname) on POS receipt

[trisdoan]

Thank you so much @legalsylvain @simahawk @ivantodorovich for your in-depth reviews

I updated the PR to take into account your inputs, including utils.py and some test cases for the function

[trisdoan]

Hi @ivantodorovich, I pushed a new commit to support feature multi-employee-per-session.

Context

• When the feature is checked, get_cashier is overridden by set_cashier in pos_hr

  • As consequences, pos_trigram is null

This change

pos_receipt_replace_user_by_triagram

• pos_trigram is defined in res.partner instead of res.users.

  • res.users inherits res.partner
  • can link res.partner and hr.employee via related field work_contact_id

pos_receipt_replace_user_by_triagram_hr

• It is a glue module between pos_receipt_replace_user_by_triagram & pos_hr
• I take advantage of the module to pass the field pos_trigram into _loader_params_hr_employee, so it can be accessed on model Pos Order

[trisdoan]

superseded by https://github.com/OCA/pos/pull/1167