[FIX] web: declare <!DOCTYPE> at the beginning of 'minimal_layout'
[FIX] web: declare <!DOCTYPE> at the beginning of 'minimal_layout'

The <!DOCTYPE> declaration must be the very first thing in an HTML
document, otherwise you may experience that the preference is given
to the "user agent stylesheet".

This is the case while printing PDF reports using the 'minimal_layout' template.
For example, layout for 'Picking Operation' report will be different in HTML and
and PDF reports. Text inside <th> will be aligned left in the HTML report, while
center in the PDF one. The issue is there since a long time, but was not obvious
enough to catch till now. (For example, in previous BS versions, explicit rule
was present to align text to the left inside <th> tag, and so the layout did not
break by luck. BSv4 afterwards, this rule was removed, shedding light on this
issue).

This commit improves the behavior while printing PDF reports by placing
<!DOCTYPE> declraration at the very beginning so that preference will be
given to custom stylesheet over "user agent stylesheet".

Task: 1880709
Closes #26846

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo