OZG-5833 fontsize use rem size

alfa-client/apps/alfa/src/styles/abstracts/_variables.scss

alfa-client/apps/alfa/src/styles/main.scss

alfa-client/apps/alfa/src/styles/material/_autocomplete.scss

alfa-client/apps/alfa/src/styles/material/_dialog.scss

...lient/apps/alfa/src/styles/material/_expansion-panel.scss

alfa-client/apps/alfa/src/styles/material/_menu.scss

alfa-client/apps/alfa/src/styles/material/_tabs.scss

alfa-client/apps/alfa/src/styles/material/_tooltip.scss

...inary-file-container/binary-file-container.component.scss

...ary-file-container/binary-file/binary-file.component.scss

.../historie-item-header/historie-item-header.component.scss

...gang-created/historie-item-vorgang-created.component.scss

...-in-vorgang/kommentar-list-item-in-vorgang.component.html

...-in-vorgang/kommentar-list-item-in-vorgang.component.scss

...s/navigation/src/lib/build-info/build-info.component.scss

.../lib/postfach-mail-form/postfach-mail-form.component.scss

...mail/postfach-mail-date/postfach-mail-date.component.scss

...ach-page-mail-list/postfach-page-mail-list.component.scss

...src/lib/ui/download-button/download-button.component.html

...ui/src/lib/ui/expansion-panel/_expansion-panel.theme.scss