[IMP] web: export improvements

* remove center buttons, corresponding features either moved to fields
list (handle / bin on exported, etc...) or removed
entirely (e.g. clear)
* replace XLS to XLSX format, increases rows# to 1048579
* add FAYT filtering of available fields
* sort available fields alphabetically (CI) always
* change export templates UI: remove buttons

TaskID: 1910953

closes odoo/odoo#32339

Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>