[FIX] web: guess resize placeholder
[FIX] web: guess resize placeholder

Before this commit, if you ask for a small image, you was waiting a picture of
64x64 but in case this image was not found, a placeholder with an other size
was returned.

Now, we try to guess the asked size, and return a resized placeholder.

This bug appear since we change the default placeholder picture with a big one

This will fix several issue and avoid to hard code size everywhere in the code

Eg: commit 92f837c and commit https://github.com/odoo/odoo/commit/154fc7d9dd550d35b7266af024e54c20e18938fc#diff-9af1af2039d16d6b544d481b4ee1ed7cR144

closes odoo/odoo#27695
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo