[FIX] l10n_ch: Fix QR bill according to specs

Reworked the structure of the HTML and the SCSS
to adhere to the official specs:

- 5mm padding inside the two main sections
- Correct font sizes
- Bold headers
- Increased the Swiss Cross inside the logo (7mm x 7mm)
- Scissors pictogram on the outline
- Dashed borders

Sizes now take the wkhtmltopdf (1/1.25 factor) shrinking
into consideration.

closes odoo/odoo#80009

Signed-off-by: William André (wan) <wan@odoo.com>