New component: the custom file input. Its purpose is to define a input of type file
with a custom trigger (button, link, etc.).
Its construction is the following:
- attributes: behaviour of the actual input (route to call, multifile, allowed
extensions etc.)
- inner template: the trigger that will fire the upload prompt when clicked
Once a file has been uploaded, the component will emit a 'uploaded' custom event
containing the files.
closesodoo/odoo#38423
Related: odoo/enterprise#6031
Signed-off-by: Géry Debongnie (ged) <ged@openerp.com>
