Major and minor style changes

Style

• use viralbeacon iframe on mobile, use self generated widget on tablet and desktop viewports
• fix visibility of hamburger menu on mobile
• fix container of cookies banner text on mobile
• fix chemical checker logo size on mobile
• fix number of slides in carousel (1 slide on mobile, 2 slides on tablet, 4 slides on desktop)
• unify page headings and its margins
• unify /images/resources/ filenames convention to kebab-case (edited 'inb-curated-covid19dataportal-data' google spreadsheet)
• unify site cards (header, body, footer)
• replace tabs with pills in health variables and show each title before paragraphs
• apply some style on search inputs in datatables
• place search boxes and download buttons in the same row next to each other
• edit buttons avoiding style like https://www.ebi.ac.uk/
• add hugo builtin function 'truncate ellipsis' in projects carousel
• edit paragraph width 80ch
• increase space between card-columns in resources and working space

Content

• place European Portal link outside of dropdown on top navbar
• in Literature section, change datatables CSV button text to 'Download as CSV', remove Excel button and adjust placing of datatables additional elements
• add link to https://cnecovid.isciii.es/ on 'Registro Covid ISCIII' logo in footer
• add vre and galaxy logos
• shuffle resources cards order

Features

• replace country flags with 'en | es' and style the active language with underline
• add 'scroll to top' floating button on bottom right corner
• edit research projects table with less columns: Project (article-like style), Reference ID
• remove topic call pills on first column "Ref." on research projects section OR hide many columns and leave only ONE COLUMN (like literature table)
• animate right arrow on links

Refactor

• create partial 'warning-manual-curation'
• replace fontawesome with bootstrap icons
• render working spaces cards by looping through a new json data file
• avoid loading several times the DataTables JS/CSS bundles; load them only once in head.html and foot.html
• avoid _bootstrap-override.scss and create custom dataportal ("dp-*") classes
• extract logic for table filtering