Template updates

[vivienlacourba]

Various updates to HTML files and their templates:

• Update link to W3C Donate page now at: https://www.w3.org/donate/
• Remove link and logo to legacy QA activity in footer
• Use https for most links
• Update css-validator.jar release URI to https://github.com/w3c/css-validator/releases/latest/download/css-validator.jar

I believe that following this PR:

• The property W3C_quality_msg that was used for the title of the QA link in the footer, can now be deprecated (the translations.html file will need to be regenerated).
• The translation kit likely needs to be refreshed.