Before this commit, in mobile, the input to handle the input event of scanner
was visible but with a negative z-index to be in the back of Odoo
viewport.
After this commit, in mobile, the input is transparent (opacity 0) and
so is not visible anymore but it's still present.
Steps to reproduce:
* Go to app switcher (in mobile)
* Scan a barcode with a hardware scanner BUG
closesodoo/odoo#45975
X-original-commit: b2b1e68e541966ad832e03fbc230418d14c85616
Signed-off-by: Adrien Dieudonné (adr) <adr@odoo.com>