[Generic] unaccent search

- added unaccent search on POS customer/partner and product
- moved unaccent from "mail.utils" to "web.utils"
- added more character to make function accurate

We might use str.normalize(from ES6) but the problem is str.normalize method can not consider some double characters i.e. accented character when normalized it returns 2 normal characters and normalize method returns single character, so here custom unaccent method is used to normalize the string

What we can improve here: We can use str.normalize method and check if string is still have unaccented charaters that we can call our unaccent method but this unaccent method is also working and performing well

closes odoo/odoo#27671